Repo created

2025-11-24 18:55:42 +01:00 · 2025-11-24 18:55:42 +01:00 · 3cef7c5092
commit 3cef7c5092
parent a629de6271
2161 changed files with 246605 additions and 2 deletions
--- a/app/k9mail/build.gradle.kts
+++ b/app/k9mail/build.gradle.kts
@ -0,0 +1,170 @@
+plugins {
+    id(ThunderbirdPlugins.App.android)
+}
+
+val testCoverageEnabled: Boolean by extra
+if (testCoverageEnabled) {
+    apply(plugin = "jacoco")
+}
+
+dependencies {
+    implementation(projects.app.ui.legacy)
+    implementation(projects.app.ui.messageListWidget)
+    implementation(projects.app.core)
+    implementation(projects.app.storage)
+    implementation(projects.app.cryptoOpenpgp)
+    implementation(projects.backend.imap)
+    implementation(projects.backend.pop3)
+    implementation(projects.backend.webdav)
+    debugImplementation(projects.backend.demo)
+
+    implementation(libs.androidx.appcompat)
+    implementation(libs.androidx.core.ktx)
+    implementation(libs.androidx.work.ktx)
+    implementation(libs.preferencex)
+    implementation(libs.timber)
+    implementation(libs.kotlinx.coroutines.core)
+
+    implementation(libs.glide)
+    annotationProcessor(libs.glide.compiler)
+
+    if (project.hasProperty("k9mail.enableLeakCanary") && project.property("k9mail.enableLeakCanary") == "true") {
+        debugImplementation(libs.leakcanary.android)
+    }
+
+    // Required for DependencyInjectionTest to be able to resolve OpenPgpApiManager
+    testImplementation(projects.plugins.openpgpApiLib.openpgpApi)
+
+    testImplementation(libs.robolectric)
+}
+
+android {
+    namespace = "com.fsck.k9"
+
+    defaultConfig {
+        applicationId = "de.monocles.mail"
+        testApplicationId = "de.monocles.mail"
+
+        versionCode = 12
+        versionName = "1.2.3"
+
+        // Keep in sync with the resource string array "supported_languages"
+        resourceConfigurations.addAll(
+            listOf(
+                "in", "br", "ca", "cs", "cy", "da", "de", "et", "en", "en_GB", "es", "eo", "eu", "fr", "gd", "gl",
+                "hr", "is", "it", "lv", "lt", "hu", "nl", "nb", "pl", "pt_PT", "pt_BR", "ru", "ro", "sq", "sk", "sl",
+                "fi", "sv", "tr", "el", "be", "bg", "sr", "uk", "iw", "ar", "fa", "ml", "ko", "zh_CN", "zh_TW", "ja",
+                "fy",
+            ),
+        )
+    }
+
+    signingConfigs {
+        if (project.hasProperty("k9mail.keyAlias") &&
+            project.hasProperty("k9mail.keyPassword") &&
+            project.hasProperty("k9mail.storeFile") &&
+            project.hasProperty("k9mail.storePassword")
+        ) {
+            create("release") {
+                keyAlias = project.property("k9mail.keyAlias") as String
+                keyPassword = project.property("k9mail.keyPassword") as String
+                storeFile = file(project.property("k9mail.storeFile") as String)
+                storePassword = project.property("k9mail.storePassword") as String
+            }
+        }
+    }
+
+    buildTypes {
+        release {
+            signingConfigs.findByName("release")?.let { releaseSigningConfig ->
+                signingConfig = releaseSigningConfig
+            }
+
+            isMinifyEnabled = true
+            proguardFiles(
+                getDefaultProguardFile("proguard-android.txt"),
+                "proguard-rules.pro",
+            )
+
+            buildConfigField(
+                "String",
+                "OAUTH_GMAIL_CLIENT_ID",
+                "\"262622259280-hhmh92rhklkg2k1tjil69epo0o9a12jm.apps.googleusercontent.com\"",
+            )
+            buildConfigField(
+                "String",
+                "OAUTH_YAHOO_CLIENT_ID",
+                "\"dj0yJmk9aHNUb3d2MW5TQnpRJmQ9WVdrOWVYbHpaRWM0YkdnbWNHbzlNQT09JnM9Y29uc3VtZXJzZWNyZXQmc3Y9MCZ4PWIz\"",
+            )
+            buildConfigField(
+                "String",
+                "OAUTH_AOL_CLIENT_ID",
+                "\"dj0yJmk9dUNqYXZhYWxOYkdRJmQ9WVdrOU1YQnZVRFZoY1ZrbWNHbzlNQT09JnM9Y29uc3VtZXJzZWNyZXQmc3Y9MCZ4PWIw\"",
+            )
+            buildConfigField("String", "OAUTH_MICROSOFT_CLIENT_ID", "\"e647013a-ada4-4114-b419-e43d250f99c5\"")
+            buildConfigField(
+                "String",
+                "OAUTH_MICROSOFT_REDIRECT_URI",
+                "\"msauth://com.fsck.k9/Dx8yUsuhyU3dYYba1aA16Wxu5eM%3D\"",
+            )
+
+            manifestPlaceholders["appAuthRedirectScheme"] = "com.fsck.k9"
+        }
+
+        debug {
+            applicationIdSuffix = ".debug"
+            enableUnitTestCoverage = testCoverageEnabled
+            enableAndroidTestCoverage = testCoverageEnabled
+
+            isMinifyEnabled = false
+
+            buildConfigField(
+                "String",
+                "OAUTH_GMAIL_CLIENT_ID",
+                "\"262622259280-5qb3vtj68d5dtudmaif4g9vd3cpar8r3.apps.googleusercontent.com\"",
+            )
+            buildConfigField(
+                "String",
+                "OAUTH_YAHOO_CLIENT_ID",
+                "\"dj0yJmk9ejRCRU1ybmZjQlVBJmQ9WVdrOVVrZEViak4xYmxZbWNHbzlNQT09JnM9Y29uc3VtZXJzZWNyZXQmc3Y9MCZ4PTZj\"",
+            )
+            buildConfigField(
+                "String",
+                "OAUTH_AOL_CLIENT_ID",
+                "\"dj0yJmk9cHYydkJkTUxHcXlYJmQ9WVdrOWVHZHhVVXN4VVV3bWNHbzlNQT09JnM9Y29uc3VtZXJzZWNyZXQmc3Y9MCZ4PTdm\"",
+            )
+            buildConfigField("String", "OAUTH_MICROSOFT_CLIENT_ID", "\"e647013a-ada4-4114-b419-e43d250f99c5\"")
+            buildConfigField(
+                "String",
+                "OAUTH_MICROSOFT_REDIRECT_URI",
+                "\"msauth://com.fsck.k9.debug/VZF2DYuLYAu4TurFd6usQB2JPts%3D\"",
+            )
+
+            manifestPlaceholders["appAuthRedirectScheme"] = "com.fsck.k9.debug"
+        }
+    }
+
+    packagingOptions {
+        jniLibs {
+            excludes += listOf("kotlin/**")
+        }
+
+        resources {
+            excludes += listOf(
+                "META-INF/DEPENDENCIES",
+                "META-INF/LICENSE",
+                "META-INF/LICENSE.txt",
+                "META-INF/NOTICE",
+                "META-INF/NOTICE.txt",
+                "META-INF/README",
+                "META-INF/README.md",
+                "META-INF/CHANGES",
+                "LICENSE.txt",
+                "META-INF/*.kotlin_module",
+                "META-INF/*.version",
+                "kotlin/**",
+                "DebugProbesKt.bin",
+            )
+        }
+    }
+}
--- a/app/k9mail/proguard-rules.pro
+++ b/app/k9mail/proguard-rules.pro
@ -0,0 +1,55 @@
+# Add project specific ProGuard rules here.
+
+-dontobfuscate
+
+# Preserve the line number information for debugging stack traces.
+-keepattributes SourceFile,LineNumberTable
+
+# Library specific rules
+-dontnote android.net.http.*
+-dontnote org.apache.commons.codec.**
+-dontnote org.apache.http.**
+-dontnote com.squareup.moshi.**
+-dontnote com.github.amlcurran.showcaseview.**
+-dontnote de.cketti.safecontentresolver.**
+-dontnote com.tokenautocomplete.**
+
+-dontwarn okio.**
+-dontwarn com.squareup.moshi.**
+
+# Glide
+-keep public class * extends com.bumptech.glide.module.AppGlideModule
+-keep public class * extends com.bumptech.glide.module.LibraryGlideModule
+-keep public enum com.bumptech.glide.load.ImageHeaderParser$** {
+  **[] $VALUES;
+  public *;
+}
+
+# Project specific rules
+-dontnote com.fsck.k9.ui.messageview.**
+-dontnote com.fsck.k9.view.**
+
+-assumevalues class * extends android.view.View {
+    boolean isInEditMode() return false;
+}
+
+-keep public class org.openintents.openpgp.**
+
+-keepclassmembers class * extends androidx.appcompat.widget.SearchView {
+    public <init>(android.content.Context);
+}
+
+# okhttp rules
+# see: https://github.com/square/okhttp/blob/master/okhttp/src/main/resources/META-INF/proguard/okhttp3.pro
+
+# JSR 305 annotations are for embedding nullability information.
+-dontwarn javax.annotation.**
+
+# A resource is loaded with a relative path so the package of this class must be preserved.
+-keepnames class okhttp3.internal.publicsuffix.PublicSuffixDatabase
+
+# Animal Sniffer compileOnly dependency to ensure APIs are compatible with older versions of Java.
+-dontwarn org.codehaus.mojo.animal_sniffer.*
+
+# OkHttp platform used only on JVM and when Conscrypt dependency is available.
+-dontwarn okhttp3.internal.platform.ConscryptPlatform
--- a/app/k9mail/src/debug/java/app/k9mail/dev/DebugConfig.kt
+++ b/app/k9mail/src/debug/java/app/k9mail/dev/DebugConfig.kt
@ -0,0 +1,12 @@
+package app.k9mail.dev
+
+import org.koin.core.module.Module
+import org.koin.core.scope.Scope
+
+fun Scope.developmentBackends() = mapOf(
+    "demo" to get<DemoBackendFactory>()
+)
+
+fun Module.developmentModuleAdditions() {
+    single { DemoBackendFactory(backendStorageFactory = get()) }
+}
--- a/app/k9mail/src/debug/java/app/k9mail/dev/DemoBackendFactory.kt
+++ b/app/k9mail/src/debug/java/app/k9mail/dev/DemoBackendFactory.kt
@ -0,0 +1,14 @@
+package app.k9mail.dev
+
+import app.k9mail.backend.demo.DemoBackend
+import com.fsck.k9.Account
+import com.fsck.k9.backend.BackendFactory
+import com.fsck.k9.backend.api.Backend
+import com.fsck.k9.mailstore.K9BackendStorageFactory
+
+class DemoBackendFactory(private val backendStorageFactory: K9BackendStorageFactory) : BackendFactory {
+    override fun createBackend(account: Account): Backend {
+        val backendStorage = backendStorageFactory.createBackendStorage(account)
+        return DemoBackend(backendStorage)
+    }
+}
--- a/app/k9mail/src/debug/res/mipmap-hdpi/icon.png
+++ b/app/k9mail/src/debug/res/mipmap-hdpi/icon.png
--- a/app/k9mail/src/debug/res/mipmap-hdpi/icon_round.png
+++ b/app/k9mail/src/debug/res/mipmap-hdpi/icon_round.png
--- a/app/k9mail/src/debug/res/mipmap-mdpi/icon.png
+++ b/app/k9mail/src/debug/res/mipmap-mdpi/icon.png
--- a/app/k9mail/src/debug/res/mipmap-mdpi/icon_round.png
+++ b/app/k9mail/src/debug/res/mipmap-mdpi/icon_round.png
--- a/app/k9mail/src/debug/res/mipmap-xhdpi/icon.png
+++ b/app/k9mail/src/debug/res/mipmap-xhdpi/icon.png
--- a/app/k9mail/src/debug/res/mipmap-xhdpi/icon_round.png
+++ b/app/k9mail/src/debug/res/mipmap-xhdpi/icon_round.png
--- a/app/k9mail/src/debug/res/mipmap-xxhdpi/icon.png
+++ b/app/k9mail/src/debug/res/mipmap-xxhdpi/icon.png
--- a/app/k9mail/src/debug/res/mipmap-xxhdpi/icon_round.png
+++ b/app/k9mail/src/debug/res/mipmap-xxhdpi/icon_round.png
--- a/app/k9mail/src/debug/res/mipmap-xxxhdpi/icon.png
+++ b/app/k9mail/src/debug/res/mipmap-xxxhdpi/icon.png
--- a/app/k9mail/src/debug/res/mipmap-xxxhdpi/icon_round.png
+++ b/app/k9mail/src/debug/res/mipmap-xxxhdpi/icon_round.png
--- a/app/k9mail/src/main/AndroidManifest.xml
+++ b/app/k9mail/src/main/AndroidManifest.xml
@ -0,0 +1,428 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:installLocation="auto">
+
+    <uses-feature
+        android:name="android.hardware.touchscreen"
+        android:required="false"/>
+
+    <supports-screens
+        android:anyDensity="true"
+        android:largeScreens="true"
+        android:normalScreens="true"
+        android:smallScreens="true"/>
+
+    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>
+    <uses-permission android:name="android.permission.READ_CONTACTS"/>
+    <uses-permission android:name="android.permission.READ_SYNC_SETTINGS"/>
+
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
+    <uses-permission android:name="android.permission.INTERNET"/>
+    <uses-permission android:name="android.permission.VIBRATE"/>
+    <uses-permission android:name="android.permission.WAKE_LOCK"/>
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
+    <uses-permission android:name="android.permission.SCHEDULE_EXACT_ALARM"/>
+
+    <application
+        android:name="com.fsck.k9.App"
+        android:allowTaskReparenting="false"
+        android:usesCleartextTraffic="true"
+        android:networkSecurityConfig="@xml/network_security_config"
+        android:icon="@drawable/ic_launcher"
+        android:label="@string/short_app_name"
+        android:theme="@style/Theme.K9.Startup"
+        android:resizeableActivity="true"
+        android:allowBackup="false"
+        android:supportsRtl="true"
+        tools:replace="android:theme"
+        tools:ignore="UnusedAttribute">
+
+        <meta-data
+            android:name="android.app.default_searchable"
+            android:value="com.fsck.k9.activity.Search"/>
+
+        <!-- TODO: Remove once minSdkVersion has been changed to 24+ -->
+        <meta-data
+            android:name="com.lge.support.SPLIT_WINDOW"
+            android:value="true"/>
+        <uses-library
+            android:name="com.sec.android.app.multiwindow"
+            android:required="false"/>
+        <meta-data
+            android:name="com.sec.android.support.multiwindow"
+            android:value="true"/>
+        <meta-data
+            android:name="com.samsung.android.sdk.multiwindow.penwindow.enable"
+            android:value="true"/>
+        <meta-data android:name="android.webkit.WebView.MetricsOptOut"
+            android:value="true" />
+
+        <activity
+            android:name=".ui.onboarding.OnboardingActivity"
+            android:label="@string/welcome_message_title" />
+
+        <activity
+            android:name=".ui.settings.account.OpenPgpAppSelectDialog"
+            android:configChanges="locale"
+            android:theme="@style/Theme.K9.Dialog.Translucent.DayNight"
+            />
+
+        <activity
+            android:name=".activity.setup.AccountSetupBasics"
+            android:configChanges="locale"
+            android:label="@string/account_setup_basics_title"/>
+
+        <activity
+            android:name=".activity.setup.AccountSetupAccountType"
+            android:configChanges="locale"
+            android:label="@string/account_setup_account_type_title"/>
+
+        <activity
+            android:name=".activity.setup.AccountSetupIncoming"
+            android:configChanges="locale"
+            android:label="@string/account_setup_incoming_title"/>
+
+        <activity
+            android:name=".activity.setup.AccountSetupComposition"
+            android:configChanges="locale"
+            android:label="@string/account_settings_composition_title"/>
+
+        <activity
+            android:name=".activity.setup.AccountSetupOutgoing"
+            android:configChanges="locale"
+            android:label="@string/account_setup_outgoing_title"/>
+
+        <activity
+            android:name=".activity.setup.AccountSetupOptions"
+            android:configChanges="locale"
+            android:label="@string/account_setup_options_title"/>
+
+        <activity
+            android:name=".activity.setup.AccountSetupNames"
+            android:configChanges="locale"
+            android:label="@string/account_setup_names_title"/>
+
+        <activity
+            android:name=".activity.ChooseAccount"
+            android:configChanges="locale"
+            android:label="@string/choose_account_title"
+            android:noHistory="true" />
+
+        <activity
+            android:name=".ui.choosefolder.ChooseFolderActivity"
+            android:configChanges="locale"
+            android:label="@string/choose_folder_title"
+            android:noHistory="true" />
+
+        <activity
+            android:name=".activity.ChooseIdentity"
+            android:configChanges="locale"
+            android:label="@string/choose_identity_title" />
+
+        <activity
+            android:name=".activity.ManageIdentities"
+            android:configChanges="locale"
+            android:label="@string/manage_identities_title"/>
+
+        <activity
+            android:name=".activity.EditIdentity"
+            android:configChanges="locale"
+            android:label="@string/edit_identity_title"/>
+
+        <activity
+            android:name=".ui.notification.DeleteConfirmationActivity"
+            android:excludeFromRecents="true"
+            android:launchMode="singleTop"
+            android:taskAffinity=""
+            android:theme="@style/Theme.K9.Dialog.Translucent.DayNight"/>
+
+        <!-- XXX Note: this activity is hacked to ignore config changes,
+             since it doesn't currently handle them correctly in code. -->
+        <activity
+            android:name=".activity.setup.AccountSetupCheckSettings"
+            android:configChanges="keyboardHidden|orientation|locale"
+            android:label="@string/account_setup_check_settings_title"/>
+
+        <activity
+            android:name=".ui.endtoend.AutocryptKeyTransferActivity"
+            android:configChanges="locale"
+            android:label="@string/ac_transfer_title"
+            />
+
+        <activity
+            android:name=".activity.MessageList"
+            android:launchMode="singleTop"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+
+                <category android:name="android.intent.category.DEFAULT"/>
+                <category android:name="android.intent.category.LAUNCHER"/>
+                <category android:name="android.intent.category.APP_EMAIL"/>
+
+                <!-- TODO: Remove once minSdkVersion has been changed to 24+ -->
+                <category android:name="android.intent.category.MULTIWINDOW_LAUNCHER"/>
+                <category android:name="android.intent.category.PENWINDOW_LAUNCHER"/>
+            </intent-filter>
+            <intent-filter>
+                <action android:name="android.intent.action.VIEW"/>
+                <data
+                    android:host="messages"
+                    android:scheme="k9mail"/>
+                <category android:name="android.intent.category.DEFAULT"/>
+            </intent-filter>
+        </activity>
+
+        <!--
+        This component is disabled by default. It will be enabled programmatically after an account has been set up.
+        -->
+        <activity
+            android:name=".activity.MessageCompose"
+            android:configChanges="locale"
+            android:enabled="false"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.SENDTO"/>
+                <data android:scheme="mailto"/>
+                <category android:name="android.intent.category.DEFAULT"/>
+            </intent-filter>
+            <intent-filter>
+                <action android:name="android.intent.action.SEND"/>
+                <data android:mimeType="*/*"/>
+                <category android:name="android.intent.category.DEFAULT"/>
+            </intent-filter>
+            <intent-filter>
+                <action android:name="android.intent.action.SEND_MULTIPLE"/>
+                <data android:mimeType="*/*"/>
+                <category android:name="android.intent.category.DEFAULT"/>
+            </intent-filter>
+            <intent-filter>
+                <action android:name="android.intent.action.VIEW"/>
+                <data android:scheme="mailto"/>
+
+                <category android:name="android.intent.category.DEFAULT"/>
+                <category android:name="android.intent.category.BROWSABLE"/>
+            </intent-filter>
+            <intent-filter>
+                <action android:name="org.autocrypt.PEER_ACTION"/>
+                <category android:name="android.intent.category.DEFAULT"/>
+            </intent-filter>
+        </activity>
+
+        <!-- Search Activity - searchable -->
+        <activity
+            android:name=".activity.Search"
+            android:configChanges="locale"
+            android:label="@string/search_action"
+            android:uiOptions="splitActionBarWhenNarrow"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.SEARCH"/>
+                <category android:name="android.intent.category.DEFAULT"/>
+            </intent-filter>
+            <meta-data
+                android:name="android.app.searchable"
+                android:resource="@xml/searchable"/>
+        </activity>
+
+        <!--
+        This component is disabled by default. It will be enabled programmatically after an account has been set up.
+        -->
+        <activity
+            android:name=".activity.LauncherShortcuts"
+            android:configChanges="locale"
+            android:label="@string/shortcuts_title"
+            android:enabled="false"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.CREATE_SHORTCUT"/>
+                <category android:name="android.intent.category.DEFAULT"/>
+            </intent-filter>
+        </activity>
+
+        <activity
+            android:name=".widget.unread.UnreadWidgetConfigurationActivity"
+            android:exported="false">
+            <intent-filter>
+                <action android:name="android.appwidget.action.APPWIDGET_CONFIGURE"/>
+            </intent-filter>
+        </activity>
+
+        <activity
+            android:name=".activity.UpgradeDatabases"
+            android:label="@string/upgrade_databases_title"/>
+
+        <activity
+            android:name=".ui.managefolders.ManageFoldersActivity"
+            android:label="@string/folders_action" />
+
+        <activity
+            android:name=".ui.settings.SettingsActivity"
+            android:label="@string/prefs_title" />
+
+        <activity
+            android:name=".ui.settings.general.GeneralSettingsActivity"
+            android:label="@string/general_settings_title" />
+
+        <activity
+            android:name=".ui.settings.account.AccountSettingsActivity"
+            android:label="@string/account_settings_title_fmt" />
+
+        <activity
+            android:name=".ui.messagesource.MessageSourceActivity"
+            android:label="@string/show_headers_action" />
+
+        <activity
+            android:name=".ui.changelog.RecentChangesActivity"
+            android:label="@string/changelog_recent_changes_title" />
+
+        <activity
+            android:name=".ui.push.PushInfoActivity"
+            android:excludeFromRecents="true"
+            android:exported="false"
+            android:label="@string/push_info_title"
+            android:taskAffinity="${applicationId}.push_info">
+            <intent-filter>
+                <action android:name="app.k9mail.action.PUSH_INFO" />
+                <category android:name="android.intent.category.DEFAULT" />
+            </intent-filter>
+        </activity>
+
+        <activity
+            android:name=".activity.setup.OAuthFlowActivity"
+            android:label="@string/account_setup_basics_title" />
+
+        <!-- This component is disabled by default (if possible). It will be enabled programmatically if necessary. -->
+        <receiver
+            android:name=".provider.UnreadWidgetProvider"
+            android:icon="@drawable/ic_launcher"
+            android:label="@string/unread_widget_label"
+            android:enabled="@bool/home_screen_widgets_enabled"
+            android:exported="false">
+            <intent-filter>
+                <action android:name="android.appwidget.action.APPWIDGET_UPDATE"/>
+            </intent-filter>
+            <meta-data
+                android:name="android.appwidget.provider"
+                android:resource="@xml/unread_widget_info"/>
+        </receiver>
+
+        <!-- This component is disabled by default (if possible). It will be enabled programmatically if necessary. -->
+        <receiver
+            android:name=".widget.list.MessageListWidgetProvider"
+            android:icon="@drawable/message_list_widget_preview"
+            android:label="@string/mail_list_widget_text"
+            android:enabled="@bool/home_screen_widgets_enabled"
+            android:exported="false">
+            <intent-filter>
+                <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
+            </intent-filter>
+            <meta-data
+                android:name="android.appwidget.provider"
+                android:resource="@xml/message_list_widget_info" />
+        </receiver>
+
+        <!-- This component is disabled by default. It will be enabled programmatically if necessary. -->
+        <receiver
+            android:name=".controller.push.BootCompleteReceiver"
+            android:exported="false"
+            android:enabled="false">
+            <intent-filter>
+                <action android:name="android.intent.action.BOOT_COMPLETED"/>
+            </intent-filter>
+        </receiver>
+
+        <service
+            android:name=".notification.NotificationActionService"/>
+
+        <service
+            android:name=".service.DatabaseUpgradeService"
+            android:exported="false"/>
+
+        <service
+            android:name="com.fsck.k9.account.AccountRemoverService"
+            android:permission="android.permission.BIND_JOB_SERVICE"/>
+
+        <service
+            android:name=".controller.push.PushService"
+            android:exported="false"
+            android:foregroundServiceType="dataSync" />
+
+        <provider
+            android:name=".provider.AttachmentProvider"
+            android:authorities="${applicationId}.attachmentprovider"
+            android:exported="false"
+            android:grantUriPermissions="true">
+
+            <meta-data
+                android:name="de.cketti.safecontentresolver.ALLOW_INTERNAL_ACCESS"
+                android:value="true" />
+
+        </provider>
+
+        <provider
+            android:name=".provider.RawMessageProvider"
+            android:authorities="${applicationId}.rawmessageprovider"
+            android:exported="false">
+
+            <meta-data
+                android:name="de.cketti.safecontentresolver.ALLOW_INTERNAL_ACCESS"
+                android:value="true" />
+
+        </provider>
+
+        <provider
+            android:name=".provider.DecryptedFileProvider"
+            android:authorities="${applicationId}.decryptedfileprovider"
+            android:exported="false"
+            android:grantUriPermissions="true">
+
+            <meta-data
+                android:name="android.support.FILE_PROVIDER_PATHS"
+                android:resource="@xml/decrypted_file_provider_paths" />
+        </provider>
+
+        <provider
+            android:name=".provider.AttachmentTempFileProvider"
+            android:authorities="${applicationId}.tempfileprovider"
+            android:exported="false"
+            android:grantUriPermissions="true">
+
+            <meta-data
+                android:name="android.support.FILE_PROVIDER_PATHS"
+                android:resource="@xml/temp_file_provider_paths" />
+        </provider>
+
+        <activity
+            android:name="net.openid.appauth.RedirectUriReceiverActivity"
+            android:exported="true"
+            tools:node="merge">
+            <intent-filter>
+                <action android:name="android.intent.action.VIEW" />
+
+                <category android:name="android.intent.category.DEFAULT" />
+                <category android:name="android.intent.category.BROWSABLE" />
+
+                <!-- Microsoft uses a special redirect URI format for Android apps -->
+                <data android:scheme="msauth" android:host="${applicationId}"/>
+            </intent-filter>
+        </activity>
+
+        <provider
+            android:name="androidx.startup.InitializationProvider"
+            android:authorities="${applicationId}.androidx-startup"
+            android:exported="false"
+            tools:node="merge">
+
+            <!-- We're using on-demand initialization for WorkManager -->
+            <meta-data
+                android:name="androidx.work.WorkManagerInitializer"
+                android:value="androidx.startup"
+                tools:node="remove" />
+
+        </provider>
+
+    </application>
+</manifest>
--- a/app/k9mail/src/main/icon-playstore.png
+++ b/app/k9mail/src/main/icon-playstore.png
--- a/app/k9mail/src/main/java/com/fsck/k9/App.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/App.kt
@ -0,0 +1,145 @@
+package com.fsck.k9
+
+import android.app.Application
+import android.content.res.Configuration
+import android.content.res.Resources
+import app.k9mail.ui.widget.list.MessageListWidgetManager
+import com.fsck.k9.activity.LauncherShortcuts
+import com.fsck.k9.activity.MessageCompose
+import com.fsck.k9.controller.MessagingController
+import com.fsck.k9.job.WorkManagerConfigurationProvider
+import com.fsck.k9.notification.NotificationChannelManager
+import com.fsck.k9.provider.UnreadWidgetProvider
+import com.fsck.k9.ui.base.AppLanguageManager
+import com.fsck.k9.ui.base.ThemeManager
+import com.fsck.k9.ui.base.extensions.currentLocale
+import com.fsck.k9.widget.list.MessageListWidgetProvider
+import java.util.Locale
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.drop
+import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.onEach
+import kotlinx.coroutines.plus
+import org.koin.android.ext.android.inject
+import timber.log.Timber
+import androidx.work.Configuration as WorkManagerConfiguration
+
+class App : Application(), WorkManagerConfiguration.Provider {
+    private val messagingController: MessagingController by inject()
+    private val messagingListenerProvider: MessagingListenerProvider by inject()
+    private val themeManager: ThemeManager by inject()
+    private val appLanguageManager: AppLanguageManager by inject()
+    private val notificationChannelManager: NotificationChannelManager by inject()
+    private val messageListWidgetManager: MessageListWidgetManager by inject()
+    private val workManagerConfigurationProvider: WorkManagerConfigurationProvider by inject()
+
+    private val appCoroutineScope: CoroutineScope = GlobalScope + Dispatchers.Main
+    private var appLanguageManagerInitialized = false
+
+    override fun onCreate() {
+        Core.earlyInit()
+
+        super.onCreate()
+
+        DI.start(this, coreModules + uiModules + appModules)
+
+        K9.init(this)
+        Core.init(this)
+        initializeAppLanguage()
+        updateNotificationChannelsOnAppLanguageChanges()
+        themeManager.init()
+        messageListWidgetManager.init()
+
+        messagingListenerProvider.listeners.forEach { listener ->
+            messagingController.addListener(listener)
+        }
+    }
+
+    private fun initializeAppLanguage() {
+        appLanguageManager.init()
+        applyOverrideLocaleToConfiguration()
+        appLanguageManagerInitialized = true
+        listenForAppLanguageChanges()
+    }
+
+    private fun applyOverrideLocaleToConfiguration() {
+        appLanguageManager.getOverrideLocale()?.let { overrideLocale ->
+            updateConfigurationWithLocale(superResources.configuration, overrideLocale)
+        }
+    }
+
+    private fun listenForAppLanguageChanges() {
+        appLanguageManager.overrideLocale
+            .drop(1) // We already applied the initial value
+            .onEach { overrideLocale ->
+                val locale = overrideLocale ?: Locale.getDefault()
+                updateConfigurationWithLocale(superResources.configuration, locale)
+            }
+            .launchIn(appCoroutineScope)
+    }
+
+    override fun onConfigurationChanged(newConfiguration: Configuration) {
+        applyOverrideLocaleToConfiguration()
+        super.onConfigurationChanged(superResources.configuration)
+    }
+
+    private fun updateConfigurationWithLocale(configuration: Configuration, locale: Locale) {
+        Timber.d("Updating application configuration with locale '$locale'")
+
+        val newConfiguration = Configuration(configuration).apply {
+            currentLocale = locale
+        }
+
+        @Suppress("DEPRECATION")
+        superResources.updateConfiguration(newConfiguration, superResources.displayMetrics)
+    }
+
+    private val superResources: Resources
+        get() = super.getResources()
+
+    // Creating a WebView instance triggers something that will cause the configuration of the Application's Resources
+    // instance to be reset to the default, i.e. not containing our locale override. Unfortunately, we're not notified
+    // about this event. So we're checking each time someone asks for the Resources instance whether we need to change
+    // the configuration again. Luckily, right now (Android 11), the platform is calling this method right after
+    // resetting the configuration.
+    override fun getResources(): Resources {
+        val resources = super.getResources()
+
+        if (appLanguageManagerInitialized) {
+            appLanguageManager.getOverrideLocale()?.let { overrideLocale ->
+                if (resources.configuration.currentLocale != overrideLocale) {
+                    Timber.w("Resources configuration was reset. Re-applying locale override.")
+                    appLanguageManager.applyOverrideLocale()
+                    applyOverrideLocaleToConfiguration()
+                }
+            }
+        }
+
+        return resources
+    }
+
+    private fun updateNotificationChannelsOnAppLanguageChanges() {
+        appLanguageManager.appLocale
+            .distinctUntilChanged()
+            .onEach { notificationChannelManager.updateChannels() }
+            .launchIn(appCoroutineScope)
+    }
+
+    override fun getWorkManagerConfiguration(): WorkManagerConfiguration {
+        return workManagerConfigurationProvider.getConfiguration()
+    }
+
+    companion object {
+        val appConfig = AppConfig(
+            componentsToDisable = listOf(
+                MessageCompose::class.java,
+                LauncherShortcuts::class.java,
+                UnreadWidgetProvider::class.java,
+                MessageListWidgetProvider::class.java
+            )
+        )
+    }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/Dependencies.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/Dependencies.kt
@ -0,0 +1,44 @@
+package com.fsck.k9
+
+import app.k9mail.ui.widget.list.messageListWidgetModule
+import com.fsck.k9.auth.createOAuthConfigurationProvider
+import com.fsck.k9.backends.backendsModule
+import com.fsck.k9.controller.ControllerExtension
+import com.fsck.k9.crypto.EncryptionExtractor
+import com.fsck.k9.crypto.openpgp.OpenPgpEncryptionExtractor
+import com.fsck.k9.notification.notificationModule
+import com.fsck.k9.preferences.K9StoragePersister
+import com.fsck.k9.preferences.StoragePersister
+import com.fsck.k9.resources.resourcesModule
+import com.fsck.k9.storage.storageModule
+import com.fsck.k9.widget.list.messageListWidgetConfigModule
+import com.fsck.k9.widget.unread.UnreadWidgetUpdateListener
+import com.fsck.k9.widget.unread.unreadWidgetModule
+import org.koin.core.qualifier.named
+import org.koin.dsl.module
+
+private val mainAppModule = module {
+    single { App.appConfig }
+    single {
+        MessagingListenerProvider(
+            listOf(
+                get<UnreadWidgetUpdateListener>()
+            )
+        )
+    }
+    single(named("controllerExtensions")) { emptyList<ControllerExtension>() }
+    single<EncryptionExtractor> { OpenPgpEncryptionExtractor.newInstance() }
+    single<StoragePersister> { K9StoragePersister(get()) }
+    single { createOAuthConfigurationProvider() }
+}
+
+val appModules = listOf(
+    mainAppModule,
+    messageListWidgetConfigModule,
+    messageListWidgetModule,
+    unreadWidgetModule,
+    notificationModule,
+    resourcesModule,
+    backendsModule,
+    storageModule
+)
--- a/app/k9mail/src/main/java/com/fsck/k9/MessagingListenerProvider.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/MessagingListenerProvider.kt
@ -0,0 +1,5 @@
+package com.fsck.k9
+
+import com.fsck.k9.controller.MessagingListener
+
+class MessagingListenerProvider(val listeners: List<MessagingListener>)
--- a/app/k9mail/src/main/java/com/fsck/k9/auth/OAuthConfigurations.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/auth/OAuthConfigurations.kt
@ -0,0 +1,46 @@
+package com.fsck.k9.auth
+
+import com.fsck.k9.BuildConfig
+import com.fsck.k9.oauth.OAuthConfiguration
+import com.fsck.k9.oauth.OAuthConfigurationProvider
+
+fun createOAuthConfigurationProvider(): OAuthConfigurationProvider {
+    val redirectUriSlash = BuildConfig.APPLICATION_ID + ":/oauth2redirect"
+    val redirectUriDoubleSlash = BuildConfig.APPLICATION_ID + "://oauth2redirect"
+
+    val googleConfig = OAuthConfiguration(
+        clientId = BuildConfig.OAUTH_GMAIL_CLIENT_ID,
+        scopes = listOf("https://mail.google.com/"),
+        authorizationEndpoint = "https://accounts.google.com/o/oauth2/v2/auth",
+        tokenEndpoint = "https://oauth2.googleapis.com/token",
+        redirectUri = redirectUriSlash
+    )
+
+    return OAuthConfigurationProvider(
+        configurations = mapOf(
+            listOf("imap.gmail.com", "imap.googlemail.com", "smtp.gmail.com", "smtp.googlemail.com") to googleConfig,
+            listOf("imap.mail.yahoo.com", "smtp.mail.yahoo.com") to OAuthConfiguration(
+                clientId = BuildConfig.OAUTH_YAHOO_CLIENT_ID,
+                scopes = listOf("mail-w"),
+                authorizationEndpoint = "https://api.login.yahoo.com/oauth2/request_auth",
+                tokenEndpoint = "https://api.login.yahoo.com/oauth2/get_token",
+                redirectUri = redirectUriDoubleSlash
+            ),
+            listOf("imap.aol.com", "smtp.aol.com") to OAuthConfiguration(
+                clientId = BuildConfig.OAUTH_AOL_CLIENT_ID,
+                scopes = listOf("mail-w"),
+                authorizationEndpoint = "https://api.login.aol.com/oauth2/request_auth",
+                tokenEndpoint = "https://api.login.aol.com/oauth2/get_token",
+                redirectUri = redirectUriDoubleSlash
+            ),
+            listOf("outlook.office365.com", "smtp.office365.com") to OAuthConfiguration(
+                clientId = BuildConfig.OAUTH_MICROSOFT_CLIENT_ID,
+                scopes = listOf("https://outlook.office.com/IMAP.AccessAsUser.All", "https://outlook.office.com/SMTP.Send", "offline_access"),
+                authorizationEndpoint = "https://login.microsoftonline.com/common/oauth2/v2.0/authorize",
+                tokenEndpoint = "https://login.microsoftonline.com/common/oauth2/v2.0/token",
+                redirectUri = BuildConfig.OAUTH_MICROSOFT_REDIRECT_URI
+            )
+        ),
+        googleConfiguration = googleConfig
+    )
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/backends/AndroidAlarmManager.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/backends/AndroidAlarmManager.kt
@ -0,0 +1,71 @@
+package com.fsck.k9.backends
+
+import android.app.PendingIntent
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import android.content.IntentFilter
+import android.os.SystemClock
+import com.fsck.k9.backend.imap.SystemAlarmManager
+import com.fsck.k9.helper.AlarmManagerCompat
+import com.fsck.k9.helper.PendingIntentCompat.FLAG_IMMUTABLE
+import java.util.concurrent.atomic.AtomicReference
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import timber.log.Timber
+
+private const val ALARM_ACTION = "com.fsck.k9.backends.ALARM"
+private const val REQUEST_CODE = 1
+
+private typealias Callback = () -> Unit
+
+class AndroidAlarmManager(
+    private val context: Context,
+    private val alarmManager: AlarmManagerCompat,
+    backgroundDispatcher: CoroutineDispatcher = Dispatchers.IO
+) : SystemAlarmManager {
+    private val coroutineScope = CoroutineScope(backgroundDispatcher)
+
+    private val pendingIntent: PendingIntent = run {
+        val intent = Intent(ALARM_ACTION).apply {
+            setPackage(context.packageName)
+        }
+
+        PendingIntent.getBroadcast(context, REQUEST_CODE, intent, FLAG_IMMUTABLE)
+    }
+
+    private val callback = AtomicReference<Callback?>(null)
+
+    init {
+        val intentFilter = IntentFilter(ALARM_ACTION)
+        context.registerReceiver(
+            object : BroadcastReceiver() {
+                override fun onReceive(context: Context?, intent: Intent?) {
+                    val callback = callback.getAndSet(null)
+                    if (callback == null) {
+                        Timber.w("Alarm triggered but 'callback' was null")
+                    } else {
+                        coroutineScope.launch {
+                            callback.invoke()
+                        }
+                    }
+                }
+            },
+            intentFilter
+        )
+    }
+
+    override fun setAlarm(triggerTime: Long, callback: Callback) {
+        this.callback.set(callback)
+        alarmManager.scheduleAlarm(triggerTime, pendingIntent)
+    }
+
+    override fun cancelAlarm() {
+        callback.set(null)
+        alarmManager.cancelAlarm(pendingIntent)
+    }
+
+    override fun now(): Long = SystemClock.elapsedRealtime()
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/backends/ImapBackendFactory.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/backends/ImapBackendFactory.kt
@ -0,0 +1,97 @@
+package com.fsck.k9.backends
+
+import android.content.Context
+import com.fsck.k9.Account
+import com.fsck.k9.backend.BackendFactory
+import com.fsck.k9.backend.api.Backend
+import com.fsck.k9.backend.imap.ImapBackend
+import com.fsck.k9.backend.imap.ImapPushConfigProvider
+import com.fsck.k9.mail.AuthType
+import com.fsck.k9.mail.power.PowerManager
+import com.fsck.k9.mail.ssl.TrustedSocketFactory
+import com.fsck.k9.mail.store.imap.IdleRefreshManager
+import com.fsck.k9.mail.store.imap.ImapStore
+import com.fsck.k9.mail.store.imap.ImapStoreConfig
+import com.fsck.k9.mail.transport.smtp.SmtpTransport
+import com.fsck.k9.mailstore.K9BackendStorageFactory
+import com.fsck.k9.preferences.AccountManager
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.map
+
+class ImapBackendFactory(
+    private val accountManager: AccountManager,
+    private val powerManager: PowerManager,
+    private val idleRefreshManager: IdleRefreshManager,
+    private val backendStorageFactory: K9BackendStorageFactory,
+    private val trustedSocketFactory: TrustedSocketFactory,
+    private val context: Context
+) : BackendFactory {
+    override fun createBackend(account: Account): Backend {
+        val accountName = account.displayName
+        val backendStorage = backendStorageFactory.createBackendStorage(account)
+        val imapStore = createImapStore(account)
+        val pushConfigProvider = createPushConfigProvider(account)
+        val smtpTransport = createSmtpTransport(account)
+
+        return ImapBackend(
+            accountName,
+            backendStorage,
+            imapStore,
+            powerManager,
+            idleRefreshManager,
+            pushConfigProvider,
+            smtpTransport
+        )
+    }
+
+    private fun createImapStore(account: Account): ImapStore {
+        val oAuth2TokenProvider = if (account.incomingServerSettings.authenticationType == AuthType.XOAUTH2) {
+            RealOAuth2TokenProvider(context, accountManager, account)
+        } else {
+            null
+        }
+
+        val config = createImapStoreConfig(account)
+        return ImapStore.create(
+            account.incomingServerSettings,
+            config,
+            trustedSocketFactory,
+            oAuth2TokenProvider
+        )
+    }
+
+    private fun createImapStoreConfig(account: Account): ImapStoreConfig {
+        return object : ImapStoreConfig {
+            override val logLabel
+                get() = account.uuid
+
+            override fun isSubscribedFoldersOnly() = account.isSubscribedFoldersOnly
+
+            override fun useCompression() = account.useCompression
+        }
+    }
+
+    private fun createSmtpTransport(account: Account): SmtpTransport {
+        val serverSettings = account.outgoingServerSettings
+        val oauth2TokenProvider = if (serverSettings.authenticationType == AuthType.XOAUTH2) {
+            RealOAuth2TokenProvider(context, accountManager, account)
+        } else {
+            null
+        }
+
+        return SmtpTransport(serverSettings, trustedSocketFactory, oauth2TokenProvider)
+    }
+
+    private fun createPushConfigProvider(account: Account) = object : ImapPushConfigProvider {
+        override val maxPushFoldersFlow: Flow<Int>
+            get() = accountManager.getAccountFlow(account.uuid)
+                .map { it.maxPushFolders }
+                .distinctUntilChanged()
+
+        override val idleRefreshMinutesFlow: Flow<Int>
+            get() = accountManager.getAccountFlow(account.uuid)
+                .map { it.idleRefreshMinutes }
+                .distinctUntilChanged()
+    }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/backends/KoinModule.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/backends/KoinModule.kt
@ -0,0 +1,51 @@
+package com.fsck.k9.backends
+
+import app.k9mail.dev.developmentBackends
+import app.k9mail.dev.developmentModuleAdditions
+import com.fsck.k9.backend.BackendManager
+import com.fsck.k9.backend.imap.BackendIdleRefreshManager
+import com.fsck.k9.backend.imap.SystemAlarmManager
+import com.fsck.k9.helper.DefaultTrustedSocketFactory
+import com.fsck.k9.mail.store.imap.IdleRefreshManager
+import com.fsck.k9.mail.store.webdav.SniHostSetter
+import org.koin.dsl.module
+
+val backendsModule = module {
+    single {
+        BackendManager(
+            mapOf(
+                "imap" to get<ImapBackendFactory>(),
+                "pop3" to get<Pop3BackendFactory>(),
+                "webdav" to get<WebDavBackendFactory>()
+            ) + developmentBackends()
+        )
+    }
+    single {
+        ImapBackendFactory(
+            accountManager = get(),
+            powerManager = get(),
+            idleRefreshManager = get(),
+            backendStorageFactory = get(),
+            trustedSocketFactory = get(),
+            context = get()
+        )
+    }
+    single<SystemAlarmManager> { AndroidAlarmManager(context = get(), alarmManager = get()) }
+    single<IdleRefreshManager> { BackendIdleRefreshManager(alarmManager = get()) }
+    single { Pop3BackendFactory(get(), get()) }
+    single {
+        WebDavBackendFactory(
+            backendStorageFactory = get(),
+            trustManagerFactory = get(),
+            sniHostSetter = get(),
+            folderRepository = get()
+        )
+    }
+    single {
+        SniHostSetter { factory, socket, hostname ->
+            DefaultTrustedSocketFactory.setSniHost(factory, socket, hostname)
+        }
+    }
+
+    developmentModuleAdditions()
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/backends/Pop3BackendFactory.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/backends/Pop3BackendFactory.kt
@ -0,0 +1,35 @@
+package com.fsck.k9.backends
+
+import com.fsck.k9.Account
+import com.fsck.k9.backend.BackendFactory
+import com.fsck.k9.backend.api.Backend
+import com.fsck.k9.backend.pop3.Pop3Backend
+import com.fsck.k9.mail.oauth.OAuth2TokenProvider
+import com.fsck.k9.mail.ssl.TrustedSocketFactory
+import com.fsck.k9.mail.store.pop3.Pop3Store
+import com.fsck.k9.mail.transport.smtp.SmtpTransport
+import com.fsck.k9.mailstore.K9BackendStorageFactory
+
+class Pop3BackendFactory(
+    private val backendStorageFactory: K9BackendStorageFactory,
+    private val trustedSocketFactory: TrustedSocketFactory
+) : BackendFactory {
+    override fun createBackend(account: Account): Backend {
+        val accountName = account.displayName
+        val backendStorage = backendStorageFactory.createBackendStorage(account)
+        val pop3Store = createPop3Store(account)
+        val smtpTransport = createSmtpTransport(account)
+        return Pop3Backend(accountName, backendStorage, pop3Store, smtpTransport)
+    }
+
+    private fun createPop3Store(account: Account): Pop3Store {
+        val serverSettings = account.incomingServerSettings
+        return Pop3Store(serverSettings, trustedSocketFactory)
+    }
+
+    private fun createSmtpTransport(account: Account): SmtpTransport {
+        val serverSettings = account.outgoingServerSettings
+        val oauth2TokenProvider: OAuth2TokenProvider? = null
+        return SmtpTransport(serverSettings, trustedSocketFactory, oauth2TokenProvider)
+    }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/backends/RealOAuth2TokenProvider.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/backends/RealOAuth2TokenProvider.kt
@ -0,0 +1,76 @@
+package com.fsck.k9.backends
+
+import android.content.Context
+import com.fsck.k9.Account
+import com.fsck.k9.mail.AuthenticationFailedException
+import com.fsck.k9.mail.oauth.OAuth2TokenProvider
+import com.fsck.k9.preferences.AccountManager
+import java.io.IOException
+import java.util.concurrent.CountDownLatch
+import java.util.concurrent.TimeUnit
+import net.openid.appauth.AuthState
+import net.openid.appauth.AuthorizationException
+import net.openid.appauth.AuthorizationException.AuthorizationRequestErrors
+import net.openid.appauth.AuthorizationException.GeneralErrors
+import net.openid.appauth.AuthorizationService
+
+class RealOAuth2TokenProvider(
+    context: Context,
+    private val accountManager: AccountManager,
+    private val account: Account
+) : OAuth2TokenProvider {
+    private val authService = AuthorizationService(context)
+    private var requestFreshToken = false
+
+    override fun getToken(timeoutMillis: Long): String {
+        val latch = CountDownLatch(1)
+        var token: String? = null
+        var exception: AuthorizationException? = null
+
+        val authState = account.oAuthState?.let { AuthState.jsonDeserialize(it) }
+            ?: throw AuthenticationFailedException("Login required")
+
+        if (requestFreshToken) {
+            authState.needsTokenRefresh = true
+        }
+
+        val oldAccessToken = authState.accessToken
+
+        authState.performActionWithFreshTokens(authService) { accessToken: String?, _, authException: AuthorizationException? ->
+            token = accessToken
+            exception = authException
+
+            latch.countDown()
+        }
+
+        latch.await(timeoutMillis, TimeUnit.MILLISECONDS)
+
+        val authException = exception
+        if (authException == GeneralErrors.NETWORK_ERROR ||
+            authException == GeneralErrors.SERVER_ERROR ||
+            authException == AuthorizationRequestErrors.SERVER_ERROR ||
+            authException == AuthorizationRequestErrors.TEMPORARILY_UNAVAILABLE
+        ) {
+            throw IOException("Error while fetching an access token", authException)
+        } else if (authException != null) {
+            account.oAuthState = null
+            accountManager.saveAccount(account)
+
+            throw AuthenticationFailedException(
+                message = "Failed to fetch an access token",
+                throwable = authException,
+                messageFromServer = authException.error
+            )
+        } else if (token != oldAccessToken) {
+            requestFreshToken = false
+            account.oAuthState = authState.jsonSerializeString()
+            accountManager.saveAccount(account)
+        }
+
+        return token ?: throw AuthenticationFailedException("Failed to fetch an access token")
+    }
+
+    override fun invalidateToken() {
+        requestFreshToken = true
+    }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/backends/WebDavBackendFactory.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/backends/WebDavBackendFactory.kt
@ -0,0 +1,35 @@
+package com.fsck.k9.backends
+
+import com.fsck.k9.Account
+import com.fsck.k9.backend.BackendFactory
+import com.fsck.k9.backend.api.Backend
+import com.fsck.k9.backend.webdav.WebDavBackend
+import com.fsck.k9.mail.ssl.TrustManagerFactory
+import com.fsck.k9.mail.store.webdav.DraftsFolderProvider
+import com.fsck.k9.mail.store.webdav.SniHostSetter
+import com.fsck.k9.mail.store.webdav.WebDavStore
+import com.fsck.k9.mailstore.FolderRepository
+import com.fsck.k9.mailstore.K9BackendStorageFactory
+
+class WebDavBackendFactory(
+    private val backendStorageFactory: K9BackendStorageFactory,
+    private val trustManagerFactory: TrustManagerFactory,
+    private val sniHostSetter: SniHostSetter,
+    private val folderRepository: FolderRepository
+) : BackendFactory {
+    override fun createBackend(account: Account): Backend {
+        val accountName = account.displayName
+        val backendStorage = backendStorageFactory.createBackendStorage(account)
+        val serverSettings = account.incomingServerSettings
+        val draftsFolderProvider = createDraftsFolderProvider(account)
+        val webDavStore = WebDavStore(trustManagerFactory, sniHostSetter, serverSettings, draftsFolderProvider)
+        return WebDavBackend(accountName, backendStorage, webDavStore)
+    }
+
+    private fun createDraftsFolderProvider(account: Account): DraftsFolderProvider {
+        return DraftsFolderProvider {
+            val draftsFolderId = account.draftsFolderId ?: error("No Drafts folder configured")
+            folderRepository.getFolderServerId(account, draftsFolderId) ?: error("Couldn't find local Drafts folder")
+        }
+    }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/glide/K9AppGlideModule.java
+++ b/app/k9mail/src/main/java/com/fsck/k9/glide/K9AppGlideModule.java
@ -0,0 +1,8 @@
+package com.fsck.k9.glide;
+
+import com.bumptech.glide.annotation.GlideModule;
+import com.bumptech.glide.module.AppGlideModule;
+
+@GlideModule
+public class K9AppGlideModule extends AppGlideModule {
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/notification/K9NotificationActionCreator.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/notification/K9NotificationActionCreator.kt
@ -0,0 +1,264 @@
+package com.fsck.k9.notification
+
+import android.app.PendingIntent
+import android.app.PendingIntent.FLAG_CANCEL_CURRENT
+import android.app.PendingIntent.FLAG_UPDATE_CURRENT
+import android.content.Context
+import android.content.Intent
+import android.net.Uri
+import com.fsck.k9.Account
+import com.fsck.k9.K9
+import com.fsck.k9.activity.MessageList
+import com.fsck.k9.activity.compose.MessageActions
+import com.fsck.k9.activity.setup.AccountSetupIncoming
+import com.fsck.k9.activity.setup.AccountSetupOutgoing
+import com.fsck.k9.controller.MessageReference
+import com.fsck.k9.helper.PendingIntentCompat.FLAG_IMMUTABLE
+import com.fsck.k9.mailstore.MessageStoreManager
+import com.fsck.k9.search.LocalSearch
+import com.fsck.k9.ui.messagelist.DefaultFolderProvider
+import com.fsck.k9.ui.notification.DeleteConfirmationActivity
+
+/**
+ * This class contains methods to create the [PendingIntent]s for the actions of our notifications.
+ *
+ * **Note:**
+ * We need to take special care to ensure the `PendingIntent`s are unique as defined in the documentation of
+ * [PendingIntent]. Otherwise selecting a notification action might perform the action on the wrong message.
+ *
+ * We add unique values to `Intent.data` so we end up with unique `PendingIntent`s.
+ *
+ * In the past we've used the notification ID as `requestCode` argument when creating a `PendingIntent`. But since we're
+ * reusing notification IDs, it's safer to make sure the `Intent` itself is unique.
+ */
+internal class K9NotificationActionCreator(
+    private val context: Context,
+    private val defaultFolderProvider: DefaultFolderProvider,
+    private val messageStoreManager: MessageStoreManager
+) : NotificationActionCreator {
+
+    override fun createViewMessagePendingIntent(messageReference: MessageReference): PendingIntent {
+        val openInUnifiedInbox = K9.isShowUnifiedInbox && isIncludedInUnifiedInbox(messageReference)
+        val intent = createMessageViewIntent(messageReference, openInUnifiedInbox)
+
+        return PendingIntent.getActivity(context, 0, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    override fun createViewFolderPendingIntent(account: Account, folderId: Long): PendingIntent {
+        val intent = createMessageListIntent(account, folderId)
+        return PendingIntent.getActivity(context, 0, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    override fun createViewMessagesPendingIntent(
+        account: Account,
+        messageReferences: List<MessageReference>
+    ): PendingIntent {
+        val folderIds = extractFolderIds(messageReferences)
+
+        val intent = if (K9.isShowUnifiedInbox && areAllIncludedInUnifiedInbox(account, folderIds)) {
+            createUnifiedInboxIntent(account)
+        } else if (folderIds.size == 1) {
+            createMessageListIntent(account, folderIds.first())
+        } else {
+            createNewMessagesIntent(account)
+        }
+
+        return PendingIntent.getActivity(context, 0, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    override fun createViewFolderListPendingIntent(account: Account): PendingIntent {
+        val intent = createMessageListIntent(account)
+        return PendingIntent.getActivity(context, 0, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    override fun createDismissAllMessagesPendingIntent(account: Account): PendingIntent {
+        val intent = NotificationActionService.createDismissAllMessagesIntent(context, account).apply {
+            data = Uri.parse("data:,dismissAll/${account.uuid}/${System.currentTimeMillis()}")
+        }
+        return PendingIntent.getService(context, 0, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    override fun createDismissMessagePendingIntent(messageReference: MessageReference): PendingIntent {
+        val intent = NotificationActionService.createDismissMessageIntent(context, messageReference).apply {
+            data = Uri.parse("data:,dismiss/${messageReference.toIdentityString()}")
+        }
+        return PendingIntent.getService(context, 0, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    override fun createReplyPendingIntent(messageReference: MessageReference): PendingIntent {
+        val intent = MessageActions.getActionReplyIntent(context, messageReference).apply {
+            data = Uri.parse("data:,reply/${messageReference.toIdentityString()}")
+        }
+        return PendingIntent.getActivity(context, 0, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    override fun createMarkMessageAsReadPendingIntent(messageReference: MessageReference): PendingIntent {
+        val intent = NotificationActionService.createMarkMessageAsReadIntent(context, messageReference).apply {
+            data = Uri.parse("data:,markAsRead/${messageReference.toIdentityString()}")
+        }
+        return PendingIntent.getService(context, 0, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    override fun createMarkAllAsReadPendingIntent(
+        account: Account,
+        messageReferences: List<MessageReference>
+    ): PendingIntent {
+        val accountUuid = account.uuid
+        val intent = NotificationActionService.createMarkAllAsReadIntent(context, accountUuid, messageReferences).apply {
+            data = Uri.parse("data:,markAllAsRead/$accountUuid/${System.currentTimeMillis()}")
+        }
+        return PendingIntent.getService(context, 0, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    override fun getEditIncomingServerSettingsIntent(account: Account): PendingIntent {
+        val intent = AccountSetupIncoming.intentActionEditIncomingSettings(context, account)
+        return PendingIntent.getActivity(context, account.accountNumber, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    override fun getEditOutgoingServerSettingsIntent(account: Account): PendingIntent {
+        val intent = AccountSetupOutgoing.intentActionEditOutgoingSettings(context, account)
+        return PendingIntent.getActivity(context, account.accountNumber, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    override fun createDeleteMessagePendingIntent(messageReference: MessageReference): PendingIntent {
+        return if (K9.isConfirmDeleteFromNotification) {
+            createDeleteConfirmationPendingIntent(messageReference)
+        } else {
+            createDeleteServicePendingIntent(messageReference)
+        }
+    }
+
+    private fun createDeleteServicePendingIntent(messageReference: MessageReference): PendingIntent {
+        val intent = NotificationActionService.createDeleteMessageIntent(context, messageReference).apply {
+            data = Uri.parse("data:,delete/${messageReference.toIdentityString()}")
+        }
+        return PendingIntent.getService(context, 0, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    private fun createDeleteConfirmationPendingIntent(messageReference: MessageReference): PendingIntent {
+        val intent = DeleteConfirmationActivity.getIntent(context, messageReference).apply {
+            data = Uri.parse("data:,deleteConfirmation/${messageReference.toIdentityString()}")
+        }
+        return PendingIntent.getActivity(context, 0, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    override fun createDeleteAllPendingIntent(
+        account: Account,
+        messageReferences: List<MessageReference>
+    ): PendingIntent {
+        return if (K9.isConfirmDeleteFromNotification) {
+            getDeleteAllConfirmationPendingIntent(messageReferences)
+        } else {
+            getDeleteAllServicePendingIntent(account, messageReferences)
+        }
+    }
+
+    private fun getDeleteAllConfirmationPendingIntent(messageReferences: List<MessageReference>): PendingIntent {
+        val intent = DeleteConfirmationActivity.getIntent(context, messageReferences).apply {
+            data = Uri.parse("data:,deleteAllConfirmation/${System.currentTimeMillis()}")
+        }
+        return PendingIntent.getActivity(context, 0, intent, FLAG_CANCEL_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    private fun getDeleteAllServicePendingIntent(
+        account: Account,
+        messageReferences: List<MessageReference>
+    ): PendingIntent {
+        val accountUuid = account.uuid
+        val intent = NotificationActionService.createDeleteAllMessagesIntent(context, accountUuid, messageReferences).apply {
+            data = Uri.parse("data:,deleteAll/$accountUuid/${System.currentTimeMillis()}")
+        }
+        return PendingIntent.getService(context, 0, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    override fun createArchiveMessagePendingIntent(messageReference: MessageReference): PendingIntent {
+        val intent = NotificationActionService.createArchiveMessageIntent(context, messageReference).apply {
+            data = Uri.parse("data:,archive/${messageReference.toIdentityString()}")
+        }
+        return PendingIntent.getService(context, 0, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    override fun createArchiveAllPendingIntent(
+        account: Account,
+        messageReferences: List<MessageReference>
+    ): PendingIntent {
+        val intent = NotificationActionService.createArchiveAllIntent(context, account, messageReferences).apply {
+            data = Uri.parse("data:,archiveAll/${account.uuid}/${System.currentTimeMillis()}")
+        }
+        return PendingIntent.getService(context, 0, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    override fun createMarkMessageAsSpamPendingIntent(messageReference: MessageReference): PendingIntent {
+        val intent = NotificationActionService.createMarkMessageAsSpamIntent(context, messageReference).apply {
+            data = Uri.parse("data:,spam/${messageReference.toIdentityString()}")
+        }
+        return PendingIntent.getService(context, 0, intent, FLAG_UPDATE_CURRENT or FLAG_IMMUTABLE)
+    }
+
+    private fun createMessageListIntent(account: Account): Intent {
+        val folderId = defaultFolderProvider.getDefaultFolder(account)
+        val search = LocalSearch().apply {
+            addAllowedFolder(folderId)
+            addAccountUuid(account.uuid)
+        }
+
+        return MessageList.intentDisplaySearch(
+            context = context,
+            search = search,
+            noThreading = false,
+            newTask = true,
+            clearTop = true
+        ).apply {
+            data = Uri.parse("data:,messageList/${account.uuid}/$folderId")
+        }
+    }
+
+    private fun createMessageListIntent(account: Account, folderId: Long): Intent {
+        val search = LocalSearch().apply {
+            addAllowedFolder(folderId)
+            addAccountUuid(account.uuid)
+        }
+
+        return MessageList.intentDisplaySearch(
+            context = context,
+            search = search,
+            noThreading = false,
+            newTask = true,
+            clearTop = true
+        ).apply {
+            data = Uri.parse("data:,messageList/${account.uuid}/$folderId")
+        }
+    }
+
+    private fun createMessageViewIntent(messageReference: MessageReference, openInUnifiedInbox: Boolean): Intent {
+        return MessageList.actionDisplayMessageIntent(context, messageReference, openInUnifiedInbox).apply {
+            data = Uri.parse("data:,messageView/${messageReference.toIdentityString()}")
+        }
+    }
+
+    private fun createUnifiedInboxIntent(account: Account): Intent {
+        return MessageList.createUnifiedInboxIntent(context, account).apply {
+            data = Uri.parse("data:,unifiedInbox/${account.uuid}")
+        }
+    }
+
+    private fun createNewMessagesIntent(account: Account): Intent {
+        return MessageList.createNewMessagesIntent(context, account).apply {
+            data = Uri.parse("data:,newMessages/${account.uuid}")
+        }
+    }
+
+    private fun extractFolderIds(messageReferences: List<MessageReference>): Set<Long> {
+        return messageReferences.asSequence().map { it.folderId }.toSet()
+    }
+
+    private fun areAllIncludedInUnifiedInbox(account: Account, folderIds: Collection<Long>): Boolean {
+        val messageStore = messageStoreManager.getMessageStore(account)
+        return messageStore.areAllIncludedInUnifiedInbox(folderIds)
+    }
+
+    private fun isIncludedInUnifiedInbox(messageReference: MessageReference): Boolean {
+        val messageStore = messageStoreManager.getMessageStore(messageReference.accountUuid)
+        return messageStore.areAllIncludedInUnifiedInbox(listOf(messageReference.folderId))
+    }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/notification/K9NotificationResourceProvider.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/notification/K9NotificationResourceProvider.kt
@ -0,0 +1,100 @@
+package com.fsck.k9.notification
+
+import android.content.Context
+import com.fsck.k9.ui.R
+
+class K9NotificationResourceProvider(private val context: Context) : NotificationResourceProvider {
+    override val iconWarning: Int = R.drawable.notification_icon_warning
+    override val iconMarkAsRead: Int = R.drawable.notification_action_mark_as_read
+    override val iconDelete: Int = R.drawable.notification_action_delete
+    override val iconReply: Int = R.drawable.notification_action_reply
+    override val iconNewMail: Int = R.drawable.notification_icon_new_mail
+    override val iconSendingMail: Int = R.drawable.notification_icon_check_mail
+    override val iconCheckingMail: Int = R.drawable.notification_icon_check_mail
+    override val wearIconMarkAsRead: Int = R.drawable.notification_action_mark_as_read
+    override val wearIconDelete: Int = R.drawable.notification_action_delete
+    override val wearIconArchive: Int = R.drawable.notification_action_archive
+    override val wearIconReplyAll: Int = R.drawable.notification_action_reply
+    override val wearIconMarkAsSpam: Int = R.drawable.notification_action_mark_as_spam
+
+    override val pushChannelName: String
+        get() = context.getString(R.string.notification_channel_push_title)
+    override val pushChannelDescription: String
+        get() = context.getString(R.string.notification_channel_push_description)
+    override val messagesChannelName: String
+        get() = context.getString(R.string.notification_channel_messages_title)
+    override val messagesChannelDescription: String
+        get() = context.getString(R.string.notification_channel_messages_description)
+    override val miscellaneousChannelName: String
+        get() = context.getString(R.string.notification_channel_miscellaneous_title)
+    override val miscellaneousChannelDescription: String
+        get() = context.getString(R.string.notification_channel_miscellaneous_description)
+
+    override fun authenticationErrorTitle(): String =
+        context.getString(R.string.notification_authentication_error_title)
+
+    override fun authenticationErrorBody(accountName: String): String =
+        context.getString(R.string.notification_authentication_error_text, accountName)
+
+    override fun notifyErrorTitle(): String = context.getString(R.string.notification_notify_error_title)
+
+    override fun notifyErrorText(): String = context.getString(R.string.notification_notify_error_text)
+
+    override fun certificateErrorTitle(): String = context.getString(R.string.notification_certificate_error_public)
+
+    override fun certificateErrorTitle(accountName: String): String =
+        context.getString(R.string.notification_certificate_error_title, accountName)
+
+    override fun certificateErrorBody(): String = context.getString(R.string.notification_certificate_error_text)
+
+    override fun newMessagesTitle(newMessagesCount: Int): String =
+        context.resources.getQuantityString(
+            R.plurals.notification_new_messages_title,
+            newMessagesCount,
+            newMessagesCount
+        )
+
+    override fun additionalMessages(overflowMessagesCount: Int, accountName: String): String =
+        context.getString(R.string.notification_additional_messages, overflowMessagesCount, accountName)
+
+    override fun previewEncrypted(): String = context.getString(R.string.preview_encrypted)
+
+    override fun noSubject(): String = context.getString(R.string.general_no_subject)
+
+    override fun recipientDisplayName(recipientDisplayName: String): String =
+        context.getString(R.string.message_to_fmt, recipientDisplayName)
+
+    override fun noSender(): String = context.getString(R.string.general_no_sender)
+
+    override fun sendFailedTitle(): String = context.getString(R.string.send_failure_subject)
+
+    override fun sendingMailTitle(): String = context.getString(R.string.notification_bg_send_title)
+
+    override fun sendingMailBody(accountName: String): String =
+        context.getString(R.string.notification_bg_send_ticker, accountName)
+
+    override fun checkingMailTicker(accountName: String, folderName: String): String =
+        context.getString(R.string.notification_bg_sync_ticker, accountName, folderName)
+
+    override fun checkingMailTitle(): String =
+        context.getString(R.string.notification_bg_sync_title)
+
+    override fun checkingMailSeparator(): String =
+        context.getString(R.string.notification_bg_title_separator)
+
+    override fun actionMarkAsRead(): String = context.getString(R.string.notification_action_mark_as_read)
+
+    override fun actionMarkAllAsRead(): String = context.getString(R.string.notification_action_mark_all_as_read)
+
+    override fun actionDelete(): String = context.getString(R.string.notification_action_delete)
+
+    override fun actionDeleteAll(): String = context.getString(R.string.notification_action_delete_all)
+
+    override fun actionReply(): String = context.getString(R.string.notification_action_reply)
+
+    override fun actionArchive(): String = context.getString(R.string.notification_action_archive)
+
+    override fun actionArchiveAll(): String = context.getString(R.string.notification_action_archive_all)
+
+    override fun actionMarkAsSpam(): String = context.getString(R.string.notification_action_spam)
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/notification/K9NotificationStrategy.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/notification/K9NotificationStrategy.kt
@ -0,0 +1,102 @@
+package com.fsck.k9.notification
+
+import app.k9mail.core.android.common.contact.ContactRepository
+import app.k9mail.core.common.mail.EmailAddress
+import com.fsck.k9.Account
+import com.fsck.k9.K9
+import com.fsck.k9.mail.Flag
+import com.fsck.k9.mail.K9MailLib
+import com.fsck.k9.mail.Message
+import com.fsck.k9.mailstore.LocalFolder
+import com.fsck.k9.mailstore.LocalFolder.isModeMismatch
+import com.fsck.k9.mailstore.LocalMessage
+import timber.log.Timber
+
+class K9NotificationStrategy(
+    private val contactRepository: ContactRepository,
+) : NotificationStrategy {
+
+    override fun shouldNotifyForMessage(
+        account: Account,
+        localFolder: LocalFolder,
+        message: LocalMessage,
+        isOldMessage: Boolean
+    ): Boolean {
+        if (!K9.isNotificationDuringQuietTimeEnabled && K9.isQuietTime) {
+            Timber.v("No notification: Quiet time is active")
+            return false
+        }
+
+        if (!account.isNotifyNewMail) {
+            Timber.v("No notification: Notifications are disabled")
+            return false
+        }
+
+        val folder = message.folder
+        if (folder != null) {
+            when (folder.databaseId) {
+                account.inboxFolderId -> {
+                    // Don't skip notifications if the Inbox folder is also configured as another special folder
+                }
+                account.trashFolderId -> {
+                    Timber.v("No notification: Message is in Trash folder")
+                    return false
+                }
+                account.draftsFolderId -> {
+                    Timber.v("No notification: Message is in Drafts folder")
+                    return false
+                }
+                account.spamFolderId -> {
+                    Timber.v("No notification: Message is in Spam folder")
+                    return false
+                }
+                account.sentFolderId -> {
+                    Timber.v("No notification: Message is in Sent folder")
+                    return false
+                }
+            }
+        }
+
+        if (isModeMismatch(account.folderDisplayMode, localFolder.displayClass)) {
+            Timber.v("No notification: Message is in folder not being displayed")
+            return false
+        }
+
+        if (isModeMismatch(account.folderNotifyNewMailMode, localFolder.notifyClass)) {
+            Timber.v("No notification: Notifications are disabled for this folder class")
+            return false
+        }
+
+        if (isOldMessage) {
+            Timber.v("No notification: Message is old")
+            return false
+        }
+
+        if (message.isSet(Flag.SEEN)) {
+            Timber.v("No notification: Message is marked as read")
+            return false
+        }
+
+        if (account.isIgnoreChatMessages && message.isChatMessage) {
+            Timber.v("No notification: Notifications for chat messages are disabled")
+            return false
+        }
+
+        if (!account.isNotifySelfNewMail && account.isAnIdentity(message.from)) {
+            Timber.v("No notification: Notifications for messages from yourself are disabled")
+            return false
+        }
+
+        if (account.isNotifyContactsMailOnly &&
+            !contactRepository.hasAnyContactFor(message.from.asList().mapNotNull { EmailAddress(it.address) })
+        ) {
+            Timber.v("No notification: Message is not from a known contact")
+            return false
+        }
+
+        return true
+    }
+
+    private val Message.isChatMessage: Boolean
+        get() = getHeader(K9MailLib.CHAT_HEADER).isNotEmpty()
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/notification/KoinModule.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/notification/KoinModule.kt
@ -0,0 +1,11 @@
+package com.fsck.k9.notification
+
+import org.koin.dsl.module
+
+val notificationModule = module {
+    single<NotificationActionCreator> {
+        K9NotificationActionCreator(context = get(), defaultFolderProvider = get(), messageStoreManager = get())
+    }
+    single<NotificationResourceProvider> { K9NotificationResourceProvider(get()) }
+    single<NotificationStrategy> { K9NotificationStrategy(get()) }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/provider/UnreadWidgetProvider.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/provider/UnreadWidgetProvider.kt
@ -0,0 +1,103 @@
+package com.fsck.k9.provider
+
+import android.app.PendingIntent
+import android.app.PendingIntent.FLAG_UPDATE_CURRENT
+import android.appwidget.AppWidgetManager
+import android.appwidget.AppWidgetProvider
+import android.content.Context
+import android.content.Intent
+import android.view.View
+import android.widget.RemoteViews
+import com.fsck.k9.EarlyInit
+import com.fsck.k9.R
+import com.fsck.k9.helper.PendingIntentCompat.FLAG_MUTABLE
+import com.fsck.k9.inject
+import com.fsck.k9.widget.unread.UnreadWidgetConfigurationActivity
+import com.fsck.k9.widget.unread.UnreadWidgetData
+import com.fsck.k9.widget.unread.UnreadWidgetRepository
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.launch
+import timber.log.Timber
+
+/**
+ * Unread home screen widget "provider"
+ *
+ * IMPORTANT: This class must not be renamed or moved, otherwise unread widgets added to the home screen using an older
+ * version of the app will stop working.
+ *
+ * The rest of the unread widget specific code can be found in the package [com.fsck.k9.widget.unread].
+ */
+class UnreadWidgetProvider : AppWidgetProvider(), EarlyInit {
+    private val repository: UnreadWidgetRepository by inject()
+
+    override fun onUpdate(context: Context, appWidgetManager: AppWidgetManager, appWidgetIds: IntArray) {
+        val pendingResult = goAsync()
+
+        GlobalScope.launch(Dispatchers.IO) {
+            updateWidgets(context, appWidgetManager, appWidgetIds)
+            pendingResult.finish()
+        }
+    }
+
+    private fun updateWidgets(context: Context, appWidgetManager: AppWidgetManager, appWidgetIds: IntArray) {
+        for (widgetId in appWidgetIds) {
+            val widgetData = repository.getWidgetData(widgetId) ?: continue
+            updateWidget(context, appWidgetManager, widgetData)
+        }
+    }
+
+    override fun onDeleted(context: Context, appWidgetIds: IntArray) {
+        for (appWidgetId in appWidgetIds) {
+            repository.deleteWidgetConfiguration(appWidgetId)
+        }
+    }
+
+    private fun updateWidget(context: Context, appWidgetManager: AppWidgetManager, data: UnreadWidgetData) {
+        val remoteViews = RemoteViews(context.packageName, R.layout.unread_widget_layout)
+
+        val appWidgetId = data.configuration.appWidgetId
+        var clickIntent: Intent? = null
+
+        try {
+            clickIntent = data.clickIntent
+            val unreadCount = data.unreadCount
+
+            if (unreadCount <= 0) {
+                // Hide TextView for unread count if there are no unread messages.
+                remoteViews.setViewVisibility(R.id.unread_count, View.GONE)
+            } else {
+                remoteViews.setViewVisibility(R.id.unread_count, View.VISIBLE)
+
+                val displayCount = if (unreadCount <= MAX_COUNT) unreadCount.toString() else "$MAX_COUNT+"
+                remoteViews.setTextViewText(R.id.unread_count, displayCount)
+            }
+
+            remoteViews.setTextViewText(R.id.title, data.title)
+        } catch (e: Exception) {
+            Timber.e(e, "Error getting widget configuration")
+        }
+
+        if (clickIntent == null) {
+            // If the widget configuration couldn't be loaded we open the configuration
+            // activity when the user clicks the widget.
+            clickIntent = Intent(context, UnreadWidgetConfigurationActivity::class.java)
+            clickIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId)
+        }
+        clickIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
+
+        val pendingIntent = PendingIntent.getActivity(
+            context,
+            appWidgetId,
+            clickIntent,
+            FLAG_UPDATE_CURRENT or FLAG_MUTABLE
+        )
+        remoteViews.setOnClickPendingIntent(R.id.unread_widget_layout, pendingIntent)
+
+        appWidgetManager.updateAppWidget(appWidgetId, remoteViews)
+    }
+
+    companion object {
+        private const val MAX_COUNT = 9999
+    }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/resources/K9AutocryptStringProvider.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/resources/K9AutocryptStringProvider.kt
@ -0,0 +1,10 @@
+package com.fsck.k9.resources
+
+import android.content.Context
+import com.fsck.k9.autocrypt.AutocryptStringProvider
+import com.fsck.k9.ui.R
+
+class K9AutocryptStringProvider(private val context: Context) : AutocryptStringProvider {
+    override fun transferMessageSubject(): String = context.getString(R.string.ac_transfer_msg_subject)
+    override fun transferMessageBody(): String = context.getString(R.string.ac_transfer_msg_body)
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/resources/K9CoreResourceProvider.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/resources/K9CoreResourceProvider.kt
@ -0,0 +1,52 @@
+package com.fsck.k9.resources
+
+import android.content.Context
+import com.fsck.k9.CoreResourceProvider
+import com.fsck.k9.notification.PushNotificationState
+import com.fsck.k9.ui.R
+
+class K9CoreResourceProvider(private val context: Context) : CoreResourceProvider {
+    override fun defaultSignature(): String = context.getString(R.string.default_signature)
+    override fun defaultIdentityDescription(): String = context.getString(R.string.default_identity_description)
+
+    override fun contactDisplayNamePrefix(): String = context.getString(R.string.message_to_label)
+    override fun contactUnknownSender(): String = context.getString(R.string.unknown_sender)
+    override fun contactUnknownRecipient(): String = context.getString(R.string.unknown_recipient)
+
+    override fun messageHeaderFrom(): String = context.getString(R.string.message_compose_quote_header_from)
+    override fun messageHeaderTo(): String = context.getString(R.string.message_compose_quote_header_to)
+    override fun messageHeaderCc(): String = context.getString(R.string.message_compose_quote_header_cc)
+    override fun messageHeaderDate(): String = context.getString(R.string.message_compose_quote_header_send_date)
+    override fun messageHeaderSubject(): String = context.getString(R.string.message_compose_quote_header_subject)
+    override fun messageHeaderSeparator(): String = context.getString(R.string.message_compose_quote_header_separator)
+
+    override fun noSubject(): String = context.getString(R.string.general_no_subject)
+
+    override fun userAgent(): String = context.getString(R.string.message_header_mua)
+    override fun encryptedSubject(): String = context.getString(R.string.encrypted_subject)
+
+    override fun replyHeader(sender: String): String =
+        context.getString(R.string.message_compose_reply_header_fmt, sender)
+
+    override fun replyHeader(sender: String, sentDate: String): String =
+        context.getString(R.string.message_compose_reply_header_fmt_with_date, sentDate, sender)
+
+    override fun searchUnifiedInboxTitle(): String = context.getString(R.string.integrated_inbox_title)
+    override fun searchUnifiedInboxDetail(): String = context.getString(R.string.integrated_inbox_detail)
+
+    override fun outboxFolderName(): String = context.getString(R.string.special_mailbox_name_outbox)
+
+    override val iconPushNotification: Int = R.drawable.ic_push_notification
+
+    override fun pushNotificationText(notificationState: PushNotificationState): String {
+        val resId = when (notificationState) {
+            PushNotificationState.INITIALIZING -> R.string.push_notification_state_initializing
+            PushNotificationState.LISTENING -> R.string.push_notification_state_listening
+            PushNotificationState.WAIT_BACKGROUND_SYNC -> R.string.push_notification_state_wait_background_sync
+            PushNotificationState.WAIT_NETWORK -> R.string.push_notification_state_wait_network
+        }
+        return context.getString(resId)
+    }
+
+    override fun pushNotificationInfoText(): String = context.getString(R.string.push_notification_info)
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/resources/KoinModule.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/resources/KoinModule.kt
@ -0,0 +1,10 @@
+package com.fsck.k9.resources
+
+import com.fsck.k9.CoreResourceProvider
+import com.fsck.k9.autocrypt.AutocryptStringProvider
+import org.koin.dsl.module
+
+val resourcesModule = module {
+    single<CoreResourceProvider> { K9CoreResourceProvider(get()) }
+    single<AutocryptStringProvider> { K9AutocryptStringProvider(get()) }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/widget/list/KoinModule.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/widget/list/KoinModule.kt
@ -0,0 +1,8 @@
+package com.fsck.k9.widget.list
+
+import app.k9mail.ui.widget.list.MessageListWidgetConfig
+import org.koin.dsl.module
+
+val messageListWidgetConfigModule = module {
+    single<MessageListWidgetConfig> { K9MessageListWidgetConfig() }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/widget/list/MessageListWidgetProvider.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/widget/list/MessageListWidgetProvider.kt
@ -0,0 +1,9 @@
+package com.fsck.k9.widget.list
+
+import app.k9mail.ui.widget.list.MessageListWidgetConfig
+
+class MessageListWidgetProvider : app.k9mail.ui.widget.list.MessageListWidgetProvider()
+
+internal class K9MessageListWidgetConfig : MessageListWidgetConfig {
+    override val providerClass = MessageListWidgetProvider::class.java
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/widget/unread/KoinModule.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/widget/unread/KoinModule.kt
@ -0,0 +1,20 @@
+package com.fsck.k9.widget.unread
+
+import org.koin.dsl.module
+
+val unreadWidgetModule = module {
+    single { UnreadWidgetRepository(context = get(), dataRetriever = get(), migrations = get()) }
+    single {
+        UnreadWidgetDataProvider(
+            context = get(),
+            preferences = get(),
+            messageCountsProvider = get(),
+            defaultFolderProvider = get(),
+            folderRepository = get(),
+            folderNameFormatter = get()
+        )
+    }
+    single { UnreadWidgetUpdater(context = get()) }
+    single { UnreadWidgetUpdateListener(unreadWidgetUpdater = get()) }
+    single { UnreadWidgetMigrations(accountRepository = get(), folderRepository = get()) }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetConfigurationActivity.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetConfigurationActivity.kt
@ -0,0 +1,39 @@
+package com.fsck.k9.widget.unread
+
+import android.appwidget.AppWidgetManager
+import android.os.Bundle
+import com.fsck.k9.R
+import com.fsck.k9.ui.base.K9Activity
+import com.fsck.k9.ui.fragmentTransaction
+import timber.log.Timber
+import com.fsck.k9.ui.R as UiR
+
+/**
+ * Activity to select an account for the unread widget.
+ */
+class UnreadWidgetConfigurationActivity : K9Activity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setLayout(R.layout.activity_unread_widget_configuration)
+        setTitle(UiR.string.unread_widget_select_account)
+
+        var appWidgetId = AppWidgetManager.INVALID_APPWIDGET_ID
+        val extras = intent.extras
+        if (extras != null) {
+            appWidgetId = extras.getInt(AppWidgetManager.EXTRA_APPWIDGET_ID, AppWidgetManager.INVALID_APPWIDGET_ID)
+        }
+
+        if (appWidgetId == AppWidgetManager.INVALID_APPWIDGET_ID) {
+            Timber.e("Received an invalid widget ID")
+            finish()
+            return
+        }
+
+        if (savedInstanceState == null) {
+            fragmentTransaction {
+                add(R.id.fragment_container, UnreadWidgetConfigurationFragment.create(appWidgetId))
+            }
+        }
+    }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetConfigurationFragment.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetConfigurationFragment.kt
@ -0,0 +1,226 @@
+package com.fsck.k9.widget.unread
+
+import android.app.Activity
+import android.appwidget.AppWidgetManager
+import android.content.Intent
+import android.os.Bundle
+import android.view.Menu
+import android.view.MenuInflater
+import android.view.MenuItem
+import android.widget.Toast
+import androidx.core.os.bundleOf
+import androidx.preference.CheckBoxPreference
+import androidx.preference.Preference
+import com.fsck.k9.Preferences
+import com.fsck.k9.R
+import com.fsck.k9.activity.ChooseAccount
+import com.fsck.k9.search.SearchAccount
+import com.fsck.k9.ui.choosefolder.ChooseFolderActivity
+import com.takisoft.preferencex.PreferenceFragmentCompat
+import org.koin.android.ext.android.inject
+import com.fsck.k9.ui.R as UiR
+
+class UnreadWidgetConfigurationFragment : PreferenceFragmentCompat() {
+    private val preferences: Preferences by inject()
+    private val repository: UnreadWidgetRepository by inject()
+    private val unreadWidgetUpdater: UnreadWidgetUpdater by inject()
+
+    private var appWidgetId: Int = AppWidgetManager.INVALID_APPWIDGET_ID
+    private lateinit var unreadAccount: Preference
+    private lateinit var unreadFolderEnabled: CheckBoxPreference
+    private lateinit var unreadFolder: Preference
+
+    private var selectedAccountUuid: String? = null
+    private var selectedFolderId: Long? = null
+    private var selectedFolderDisplayName: String? = null
+
+    override fun onCreatePreferencesFix(savedInstanceState: Bundle?, rootKey: String?) {
+        setHasOptionsMenu(true)
+        setPreferencesFromResource(R.xml.unread_widget_configuration, rootKey)
+
+        appWidgetId = arguments?.getInt(ARGUMENT_APP_WIDGET_ID) ?: error("Missing argument '$ARGUMENT_APP_WIDGET_ID'")
+
+        unreadAccount = findPreference(PREFERENCE_UNREAD_ACCOUNT)!!
+        unreadAccount.onPreferenceClickListener = Preference.OnPreferenceClickListener {
+            val intent = Intent(requireContext(), ChooseAccount::class.java)
+            startActivityForResult(intent, REQUEST_CHOOSE_ACCOUNT)
+            false
+        }
+
+        unreadFolderEnabled = findPreference(PREFERENCE_UNREAD_FOLDER_ENABLED)!!
+        unreadFolderEnabled.onPreferenceChangeListener = Preference.OnPreferenceChangeListener { _, _ ->
+            unreadFolder.summary = getString(UiR.string.unread_widget_folder_summary)
+            selectedFolderId = null
+            selectedFolderDisplayName = null
+            true
+        }
+
+        unreadFolder = findPreference(PREFERENCE_UNREAD_FOLDER)!!
+        unreadFolder.onPreferenceClickListener = Preference.OnPreferenceClickListener {
+            val intent = ChooseFolderActivity.buildLaunchIntent(
+                context = requireContext(),
+                action = ChooseFolderActivity.Action.CHOOSE,
+                accountUuid = selectedAccountUuid!!,
+                showDisplayableOnly = true
+            )
+            startActivityForResult(intent, REQUEST_CHOOSE_FOLDER)
+            false
+        }
+
+        if (savedInstanceState != null) {
+            restoreInstanceState(savedInstanceState)
+        }
+    }
+
+    override fun onSaveInstanceState(outState: Bundle) {
+        super.onSaveInstanceState(outState)
+        outState.putString(STATE_SELECTED_ACCOUNT_UUID, selectedAccountUuid)
+        outState.putLongIfPresent(STATE_SELECTED_FOLDER_ID, selectedFolderId)
+        outState.putString(STATE_SELECTED_FOLDER_DISPLAY_NAME, selectedFolderDisplayName)
+    }
+
+    private fun restoreInstanceState(savedInstanceState: Bundle) {
+        val accountUuid = savedInstanceState.getString(STATE_SELECTED_ACCOUNT_UUID)
+        if (accountUuid != null) {
+            handleChooseAccount(accountUuid)
+            val folderId = savedInstanceState.getLongOrNull(STATE_SELECTED_FOLDER_ID)
+            val folderSummary = savedInstanceState.getString(STATE_SELECTED_FOLDER_DISPLAY_NAME)
+            if (folderId != null && folderSummary != null) {
+                handleChooseFolder(folderId, folderSummary)
+            }
+        }
+    }
+
+    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
+        if (resultCode == Activity.RESULT_OK && data != null) {
+            when (requestCode) {
+                REQUEST_CHOOSE_ACCOUNT -> {
+                    val accountUuid = data.getStringExtra(ChooseAccount.EXTRA_ACCOUNT_UUID)!!
+                    handleChooseAccount(accountUuid)
+                }
+                REQUEST_CHOOSE_FOLDER -> {
+                    val folderId = data.getLongExtra(ChooseFolderActivity.RESULT_SELECTED_FOLDER_ID, -1L)
+                    val folderDisplayName = data.getStringExtra(ChooseFolderActivity.RESULT_FOLDER_DISPLAY_NAME)!!
+                    handleChooseFolder(folderId, folderDisplayName)
+                }
+            }
+        }
+        super.onActivityResult(requestCode, resultCode, data)
+    }
+
+    private fun handleChooseAccount(accountUuid: String) {
+        val userSelectedSameAccount = accountUuid == selectedAccountUuid
+        if (userSelectedSameAccount) {
+            return
+        }
+
+        selectedAccountUuid = accountUuid
+        selectedFolderId = null
+        selectedFolderDisplayName = null
+        unreadFolder.summary = getString(UiR.string.unread_widget_folder_summary)
+        if (SearchAccount.UNIFIED_INBOX == selectedAccountUuid) {
+            handleSearchAccount()
+        } else {
+            handleRegularAccount()
+        }
+    }
+
+    private fun handleSearchAccount() {
+        if (SearchAccount.UNIFIED_INBOX == selectedAccountUuid) {
+            unreadAccount.setSummary(UiR.string.unread_widget_unified_inbox_account_summary)
+        }
+        unreadFolderEnabled.isEnabled = false
+        unreadFolderEnabled.isChecked = false
+        unreadFolder.isEnabled = false
+        selectedFolderId = null
+        selectedFolderDisplayName = null
+    }
+
+    private fun handleRegularAccount() {
+        val selectedAccount = preferences.getAccount(selectedAccountUuid!!)
+            ?: error("Account $selectedAccountUuid not found")
+
+        unreadAccount.summary = selectedAccount.displayName
+        unreadFolderEnabled.isEnabled = true
+        unreadFolder.isEnabled = true
+    }
+
+    private fun handleChooseFolder(folderId: Long, folderDisplayName: String) {
+        selectedFolderId = folderId
+        selectedFolderDisplayName = folderDisplayName
+        unreadFolder.summary = folderDisplayName
+    }
+
+    override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
+        inflater.inflate(R.menu.unread_widget_option, menu)
+    }
+
+    override fun onOptionsItemSelected(item: MenuItem): Boolean {
+        return when (item.itemId) {
+            R.id.done -> {
+                if (validateWidget()) {
+                    updateWidgetAndExit()
+                }
+                true
+            }
+            else -> super.onOptionsItemSelected(item)
+        }
+    }
+
+    private fun validateWidget(): Boolean {
+        if (selectedAccountUuid == null) {
+            Toast.makeText(requireContext(), UiR.string.unread_widget_account_not_selected, Toast.LENGTH_LONG).show()
+            return false
+        } else if (unreadFolderEnabled.isChecked && selectedFolderId == null) {
+            Toast.makeText(requireContext(), UiR.string.unread_widget_folder_not_selected, Toast.LENGTH_LONG).show()
+            return false
+        }
+        return true
+    }
+
+    private fun updateWidgetAndExit() {
+        val configuration = UnreadWidgetConfiguration(appWidgetId, selectedAccountUuid!!, selectedFolderId)
+        repository.saveWidgetConfiguration(configuration)
+
+        unreadWidgetUpdater.update(appWidgetId)
+
+        // Let the caller know that the configuration was successful
+        val resultValue = Intent()
+        resultValue.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId)
+
+        val activity = requireActivity()
+        activity.setResult(Activity.RESULT_OK, resultValue)
+        activity.finish()
+    }
+
+    private fun Bundle.putLongIfPresent(key: String, value: Long?) {
+        if (value != null) {
+            putLong(key, value)
+        }
+    }
+
+    private fun Bundle.getLongOrNull(key: String): Long? {
+        return if (containsKey(key)) getLong(key) else null
+    }
+
+    companion object {
+        private const val ARGUMENT_APP_WIDGET_ID = "app_widget_id"
+
+        private const val PREFERENCE_UNREAD_ACCOUNT = "unread_account"
+        private const val PREFERENCE_UNREAD_FOLDER_ENABLED = "unread_folder_enabled"
+        private const val PREFERENCE_UNREAD_FOLDER = "unread_folder"
+
+        private const val REQUEST_CHOOSE_ACCOUNT = 1
+        private const val REQUEST_CHOOSE_FOLDER = 2
+
+        private const val STATE_SELECTED_ACCOUNT_UUID = "com.fsck.k9.widget.unread.selectedAccountUuid"
+        private const val STATE_SELECTED_FOLDER_ID = "com.fsck.k9.widget.unread.selectedFolderId"
+        private const val STATE_SELECTED_FOLDER_DISPLAY_NAME = "com.fsck.k9.widget.unread.selectedFolderDisplayName"
+
+        fun create(appWidgetId: Int): UnreadWidgetConfigurationFragment {
+            return UnreadWidgetConfigurationFragment().apply {
+                arguments = bundleOf(ARGUMENT_APP_WIDGET_ID to appWidgetId)
+            }
+        }
+    }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetData.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetData.kt
@ -0,0 +1,10 @@
+package com.fsck.k9.widget.unread
+
+import android.content.Intent
+
+data class UnreadWidgetData(
+    val configuration: UnreadWidgetConfiguration,
+    val title: String,
+    val unreadCount: Int,
+    val clickIntent: Intent
+)
--- a/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetDataProvider.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetDataProvider.kt
@ -0,0 +1,98 @@
+package com.fsck.k9.widget.unread
+
+import android.content.Context
+import android.content.Intent
+import com.fsck.k9.Account
+import com.fsck.k9.Preferences
+import com.fsck.k9.activity.MessageList
+import com.fsck.k9.controller.MessageCountsProvider
+import com.fsck.k9.mailstore.FolderRepository
+import com.fsck.k9.search.LocalSearch
+import com.fsck.k9.search.SearchAccount
+import com.fsck.k9.ui.folders.FolderNameFormatter
+import com.fsck.k9.ui.messagelist.DefaultFolderProvider
+import timber.log.Timber
+import com.fsck.k9.ui.R as UiR
+
+class UnreadWidgetDataProvider(
+    private val context: Context,
+    private val preferences: Preferences,
+    private val messageCountsProvider: MessageCountsProvider,
+    private val defaultFolderProvider: DefaultFolderProvider,
+    private val folderRepository: FolderRepository,
+    private val folderNameFormatter: FolderNameFormatter
+) {
+    fun loadUnreadWidgetData(configuration: UnreadWidgetConfiguration): UnreadWidgetData? = with(configuration) {
+        if (SearchAccount.UNIFIED_INBOX == accountUuid) {
+            loadSearchAccountData(configuration)
+        } else if (folderId != null) {
+            loadFolderData(configuration)
+        } else {
+            loadAccountData(configuration)
+        }
+    }
+
+    private fun loadSearchAccountData(configuration: UnreadWidgetConfiguration): UnreadWidgetData {
+        val searchAccount = getSearchAccount(configuration.accountUuid)
+        val title = searchAccount.name
+        val unreadCount = messageCountsProvider.getMessageCounts(searchAccount).unread
+        val clickIntent = MessageList.intentDisplaySearch(context, searchAccount.relatedSearch, false, true, true)
+
+        return UnreadWidgetData(configuration, title, unreadCount, clickIntent)
+    }
+
+    private fun getSearchAccount(accountUuid: String): SearchAccount = when (accountUuid) {
+        SearchAccount.UNIFIED_INBOX -> SearchAccount.createUnifiedInboxAccount()
+        else -> throw AssertionError("SearchAccount expected")
+    }
+
+    private fun loadAccountData(configuration: UnreadWidgetConfiguration): UnreadWidgetData? {
+        val account = preferences.getAccount(configuration.accountUuid) ?: return null
+        val title = account.displayName
+        val unreadCount = messageCountsProvider.getMessageCounts(account).unread
+        val clickIntent = getClickIntentForAccount(account)
+
+        return UnreadWidgetData(configuration, title, unreadCount, clickIntent)
+    }
+
+    private fun getClickIntentForAccount(account: Account): Intent {
+        val folderId = defaultFolderProvider.getDefaultFolder(account)
+        return getClickIntentForFolder(account, folderId)
+    }
+
+    private fun loadFolderData(configuration: UnreadWidgetConfiguration): UnreadWidgetData? {
+        val accountUuid = configuration.accountUuid
+        val account = preferences.getAccount(accountUuid) ?: return null
+        val folderId = configuration.folderId ?: return null
+
+        val accountName = account.displayName
+        val folderDisplayName = getFolderDisplayName(account, folderId)
+        val title = context.getString(UiR.string.unread_widget_title, accountName, folderDisplayName)
+
+        val unreadCount = messageCountsProvider.getUnreadMessageCount(account, folderId)
+
+        val clickIntent = getClickIntentForFolder(account, folderId)
+
+        return UnreadWidgetData(configuration, title, unreadCount, clickIntent)
+    }
+
+    private fun getFolderDisplayName(account: Account, folderId: Long): String {
+        val folder = folderRepository.getFolder(account, folderId)
+        return if (folder != null) {
+            folderNameFormatter.displayName(folder)
+        } else {
+            Timber.e("Error loading folder for account %s, folder ID: %d", account, folderId)
+            ""
+        }
+    }
+
+    private fun getClickIntentForFolder(account: Account, folderId: Long): Intent {
+        val search = LocalSearch()
+        search.addAllowedFolder(folderId)
+        search.addAccountUuid(account.uuid)
+
+        val clickIntent = MessageList.intentDisplaySearch(context, search, false, true, true)
+        clickIntent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT)
+        return clickIntent
+    }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetMigrations.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetMigrations.kt
@ -0,0 +1,44 @@
+package com.fsck.k9.widget.unread
+
+import android.content.SharedPreferences
+import androidx.core.content.edit
+import com.fsck.k9.Preferences
+import com.fsck.k9.mailstore.FolderRepository
+import com.fsck.k9.widget.unread.UnreadWidgetRepository.Companion.PREFS_VERSION
+import com.fsck.k9.widget.unread.UnreadWidgetRepository.Companion.PREF_VERSION_KEY
+
+internal class UnreadWidgetMigrations(
+    private val accountRepository: Preferences,
+    private val folderRepository: FolderRepository
+) {
+    fun upgradePreferences(preferences: SharedPreferences, version: Int) {
+        if (version < 2) rewriteFolderNameToFolderId(preferences)
+
+        preferences.setVersion(PREFS_VERSION)
+    }
+
+    private fun SharedPreferences.setVersion(version: Int) {
+        edit { putInt(PREF_VERSION_KEY, version) }
+    }
+
+    private fun rewriteFolderNameToFolderId(preferences: SharedPreferences) {
+        val widgetIds = preferences.all.keys
+            .filter { it.endsWith(".folder_name") }
+            .map { it.split(".")[1] }
+
+        preferences.edit {
+            for (widgetId in widgetIds) {
+                val accountUuid = preferences.getString("unread_widget.$widgetId", null) ?: continue
+                val account = accountRepository.getAccount(accountUuid) ?: continue
+
+                val folderServerId = preferences.getString("unread_widget.$widgetId.folder_name", null)
+                if (folderServerId != null) {
+                    val folderId = folderRepository.getFolderId(account, folderServerId)
+                    putString("unread_widget.$widgetId.folder_id", folderId?.toString())
+                }
+
+                remove("unread_widget.$widgetId.folder_name")
+            }
+        }
+    }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetRepository.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetRepository.kt
@ -0,0 +1,62 @@
+package com.fsck.k9.widget.unread
+
+import android.content.Context
+import android.content.SharedPreferences
+
+internal class UnreadWidgetRepository(
+    private val context: Context,
+    private val dataRetriever: UnreadWidgetDataProvider,
+    private val migrations: UnreadWidgetMigrations
+) {
+
+    fun saveWidgetConfiguration(configuration: UnreadWidgetConfiguration) {
+        val appWidgetId = configuration.appWidgetId
+        val editor = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE).edit()
+        editor.putString(PREF_PREFIX_KEY + appWidgetId, configuration.accountUuid)
+        editor.putString(PREF_PREFIX_KEY + appWidgetId + PREF_FOLDER_ID_SUFFIX_KEY, configuration.folderId?.toString())
+        editor.apply()
+    }
+
+    fun getWidgetData(appWidgetId: Int): UnreadWidgetData? {
+        val prefs = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE)
+
+        val version = prefs.getInt(PREF_VERSION_KEY, 1)
+        if (version != PREFS_VERSION) {
+            upgradePreferences(version, prefs)
+        }
+
+        val accountUuid = prefs.getString(PREF_PREFIX_KEY + appWidgetId, null) ?: return null
+        val folderId = prefs.getString(PREF_PREFIX_KEY + appWidgetId + PREF_FOLDER_ID_SUFFIX_KEY, null)?.toLongOrNull()
+
+        val configuration = UnreadWidgetConfiguration(appWidgetId, accountUuid, folderId)
+
+        return dataRetriever.loadUnreadWidgetData(configuration)
+    }
+
+    private fun upgradePreferences(version: Int, preferences: SharedPreferences) {
+        if (version > PREFS_VERSION) {
+            error("UnreadWidgetRepository: Version downgrades are not supported")
+        } else {
+            migrations.upgradePreferences(preferences, version)
+        }
+    }
+
+    fun deleteWidgetConfiguration(appWidgetId: Int) {
+        val editor = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE).edit()
+        editor.remove(PREF_PREFIX_KEY + appWidgetId)
+        editor.remove(PREF_PREFIX_KEY + appWidgetId + PREF_FOLDER_ID_SUFFIX_KEY)
+        editor.apply()
+    }
+
+    companion object {
+        internal const val PREFS_VERSION = 2
+        internal const val PREF_VERSION_KEY = "version"
+
+        private const val PREFS_NAME = "unread_widget_configuration.xml"
+
+        private const val PREF_PREFIX_KEY = "unread_widget."
+        private const val PREF_FOLDER_ID_SUFFIX_KEY = ".folder_id"
+    }
+}
+
+data class UnreadWidgetConfiguration(val appWidgetId: Int, val accountUuid: String, val folderId: Long?)
--- a/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetUpdateListener.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetUpdateListener.kt
@ -0,0 +1,29 @@
+package com.fsck.k9.widget.unread
+
+import com.fsck.k9.Account
+import com.fsck.k9.controller.SimpleMessagingListener
+import com.fsck.k9.mail.Message
+import timber.log.Timber
+
+class UnreadWidgetUpdateListener(private val unreadWidgetUpdater: UnreadWidgetUpdater) : SimpleMessagingListener() {
+
+    private fun updateUnreadWidget() {
+        try {
+            unreadWidgetUpdater.updateAll()
+        } catch (e: Exception) {
+            Timber.e(e, "Error while updating unread widget(s)")
+        }
+    }
+
+    override fun synchronizeMailboxRemovedMessage(account: Account, folderServerId: String, messageServerId: String) {
+        updateUnreadWidget()
+    }
+
+    override fun synchronizeMailboxNewMessage(account: Account, folderServerId: String, message: Message) {
+        updateUnreadWidget()
+    }
+
+    override fun folderStatusChanged(account: Account, folderId: Long) {
+        updateUnreadWidget()
+    }
+}
--- a/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetUpdater.kt
+++ b/app/k9mail/src/main/java/com/fsck/k9/widget/unread/UnreadWidgetUpdater.kt
@ -0,0 +1,30 @@
+package com.fsck.k9.widget.unread
+
+import android.appwidget.AppWidgetManager
+import android.content.ComponentName
+import android.content.Context
+import android.content.Intent
+import com.fsck.k9.provider.UnreadWidgetProvider
+
+class UnreadWidgetUpdater(private val context: Context) {
+    private val appWidgetManager = AppWidgetManager.getInstance(context)
+
+    fun updateAll() {
+        val thisWidget = ComponentName(context, UnreadWidgetProvider::class.java)
+        val widgetIds = appWidgetManager.getAppWidgetIds(thisWidget)
+
+        updateWidgets(context, widgetIds)
+    }
+
+    fun update(widgetId: Int) {
+        updateWidgets(context, intArrayOf(widgetId))
+    }
+
+    private fun updateWidgets(context: Context, widgetIds: IntArray) {
+        val updateIntent = Intent(context, UnreadWidgetProvider::class.java)
+        updateIntent.action = AppWidgetManager.ACTION_APPWIDGET_UPDATE
+        updateIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, widgetIds)
+
+        context.sendBroadcast(updateIntent)
+    }
+}
--- a/app/k9mail/src/main/res/drawable-hdpi/ic_unread_widget.png
+++ b/app/k9mail/src/main/res/drawable-hdpi/ic_unread_widget.png
--- a/app/k9mail/src/main/res/drawable-hdpi/ic_unread_widget_selected.png
+++ b/app/k9mail/src/main/res/drawable-hdpi/ic_unread_widget_selected.png
--- a/app/k9mail/src/main/res/drawable-mdpi/ic_unread_widget.png
+++ b/app/k9mail/src/main/res/drawable-mdpi/ic_unread_widget.png
--- a/app/k9mail/src/main/res/drawable-mdpi/ic_unread_widget_selected.png
+++ b/app/k9mail/src/main/res/drawable-mdpi/ic_unread_widget_selected.png
--- a/app/k9mail/src/main/res/drawable-xhdpi/ic_unread_widget.png
+++ b/app/k9mail/src/main/res/drawable-xhdpi/ic_unread_widget.png
--- a/app/k9mail/src/main/res/drawable-xhdpi/ic_unread_widget_selected.png
+++ b/app/k9mail/src/main/res/drawable-xhdpi/ic_unread_widget_selected.png
--- a/app/k9mail/src/main/res/drawable/ic_launcher_foreground.xml
+++ b/app/k9mail/src/main/res/drawable/ic_launcher_foreground.xml
@ -0,0 +1,17 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="120dp"
+    android:height="120dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+  <group android:scaleX="0.28915662"
+      android:scaleY="0.28915662"
+      android:translateX="30.24"
+      android:translateY="38.246574">
+    <path
+        android:pathData="m156.24,1.29 l-0.16,-0.19 -0.09,0.07a14.17,14.17 0,0 0,-5.65 -1.17L14.01,0a14.22,14.22 0,0 0,-5.66 1.17l-0.09,-0.07 -0.15,0.19a13.61,13.61 0,0 0,-8.09 12.34v81.7a13.82,13.82 0,0 0,14 13.63h136.32a13.83,13.83 0,0 0,14 -13.63v-81.7a13.61,13.61 0,0 0,-8.1 -12.34zM145.04,9.85 L82.19,59.62 19.32,9.85zM150.34,99.11L14.01,99.11a3.84,3.84 0,0 1,-3.88 -3.78v-80.06l72.06,57.05 72,-57v80.05a3.84,3.84 0,0 1,-3.85 3.71z"
+        android:fillColor="#7189c5"/>
+    <path
+        android:pathData="M68.73,67.62A31.33,31.33 0,0 0,59.56 71.08a48.9,48.9 0,0 0,-7.21 4.81c-4.28,3.4 -16.23,11.93 -28.73,12.23a42.87,42.87 0,0 1,-22.2 -5.74,9.77 9.77,0 0,1 -1.42,-1 12.4,12.4 0,0 0,2.87 7.95c6.25,7.51 16.24,16.34 29,17.06 12.62,0.71 20.54,-0.94 32.22,-6.48 10.27,-4.88 16.21,-14.08 18,-21.08h0.09c1.8,7 7.74,16.2 18,21.08 11.68,5.54 19.6,7.19 32.22,6.48 12.62,-0.71 22.69,-9.48 29,-17a12.59,12.59 0,0 0,2.92 -8.08v0a11.19,11.19 0,0 1,-1.7 1.2,42.85 42.85,0 0,1 -21.9,5.58c-12.5,-0.3 -24.45,-8.83 -28.73,-12.23a48.9,48.9 0,0 0,-7.21 -4.81,31.33 31.33,0 0,0 -9.15,-3.46c-2.75,-0.47 -5.26,-0.81 -7.71,-0.16a11,11 0,0 0,-5 3,3.56 3.56,0 0,0 -0.77,1.16 3.75,3.75 0,0 0,-0.78 -1.16,11.09 11.09,0 0,0 -5,-3c-2.38,-0.62 -4.89,-0.28 -7.64,0.19z"
+        android:fillColor="#3e5ea2"/>
+  </group>
+</vector>
--- a/app/k9mail/src/main/res/drawable/unread_count_background.xml
+++ b/app/k9mail/src/main/res/drawable/unread_count_background.xml
@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<shape
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="rectangle">
+
+    <solid android:color="#ffcc0000"/>
+    <corners android:radius="17dp"/>
+
+</shape>
--- a/app/k9mail/src/main/res/drawable/unread_widget_background.xml
+++ b/app/k9mail/src/main/res/drawable/unread_widget_background.xml
@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    
+    <!-- FIXME: find a nicer looking way than using 'menuitem_background' -->
+    <item android:drawable="@android:drawable/menuitem_background"
+        android:state_pressed="true" />
+    
+    <item android:drawable="@android:drawable/menuitem_background"
+        android:state_focused="true"
+        android:state_enabled="true"
+        android:state_window_focused="true" />
+    
+    <item android:drawable="@android:color/transparent" />
+
+</selector>
--- a/app/k9mail/src/main/res/drawable/unread_widget_icon.xml
+++ b/app/k9mail/src/main/res/drawable/unread_widget_icon.xml
@ -0,0 +1,6 @@
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:drawable="@drawable/ic_unread_widget_selected" android:state_pressed="true" />
+    <item android:drawable="@drawable/ic_unread_widget_selected" android:state_focused="true" />
+    <item android:drawable="@drawable/ic_unread_widget_selected" android:state_selected="true" />
+    <item android:drawable="@drawable/ic_unread_widget" />
+</selector>
--- a/app/k9mail/src/main/res/layout/activity_unread_widget_configuration.xml
+++ b/app/k9mail/src/main/res/layout/activity_unread_widget_configuration.xml
@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical"
+    tools:context=".widget.unread.UnreadWidgetConfigurationActivity">
+
+    <include layout="@layout/toolbar" />
+
+    <androidx.fragment.app.FragmentContainerView
+        android:id="@+id/fragment_container"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_weight="1" />
+
+</LinearLayout>
--- a/app/k9mail/src/main/res/layout/unread_widget_layout.xml
+++ b/app/k9mail/src/main/res/layout/unread_widget_layout.xml
@ -0,0 +1,55 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    style="@style/UnreadWidgetContainer"
+    android:id="@+id/unread_widget_layout"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical"
+    android:clickable="true"
+    android:focusable="true">
+
+    <FrameLayout
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content">
+
+        <ImageView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:scaleType="fitCenter"
+            android:src="@drawable/unread_widget_icon" />
+
+        <TextView
+            android:id="@+id/unread_count"
+            android:visibility="gone"
+            android:textSize="12dp"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="end|bottom"
+            android:paddingTop="0.5dp"
+            android:paddingBottom="0.5dp"
+            android:paddingLeft="5dp"
+            android:paddingRight="5dp"
+            android:background="@drawable/unread_count_background"
+            android:textColor="#ffffff"
+            tools:ignore="SpUsage"/>
+
+    </FrameLayout>
+
+    <TextView
+        style="@style/UnreadWidgetTextView"
+        android:id="@+id/title"
+        android:text="@string/app_name"
+        android:ellipsize="marquee"
+        android:paddingTop="1dp"
+        android:paddingBottom="1dp"
+        android:paddingLeft="4dp"
+        android:paddingRight="4dp"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="center_horizontal"
+        android:layout_marginTop="3dp"
+        android:singleLine="true" />
+
+</LinearLayout>
--- a/app/k9mail/src/main/res/menu/unread_widget_option.xml
+++ b/app/k9mail/src/main/res/menu/unread_widget_option.xml
@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+    <item
+        android:id="@+id/done"
+        android:title="@string/unread_widget_action_done"
+        app:showAsAction="always"
+        android:icon="?attr/iconActionSave"
+        />
+</menu>
--- a/app/k9mail/src/main/res/mipmap-anydpi-v26/icon.xml
+++ b/app/k9mail/src/main/res/mipmap-anydpi-v26/icon.xml
@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@color/ic_launcher_background"/>
+    <foreground android:drawable="@drawable/ic_launcher_foreground"/>
+</adaptive-icon>
--- a/app/k9mail/src/main/res/mipmap-anydpi-v26/icon_round.xml
+++ b/app/k9mail/src/main/res/mipmap-anydpi-v26/icon_round.xml
@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@color/ic_launcher_background"/>
+    <foreground android:drawable="@drawable/ic_launcher_foreground"/>
+</adaptive-icon>
--- a/app/k9mail/src/main/res/mipmap-hdpi/icon.png
+++ b/app/k9mail/src/main/res/mipmap-hdpi/icon.png
--- a/app/k9mail/src/main/res/mipmap-hdpi/icon_foreground.png
+++ b/app/k9mail/src/main/res/mipmap-hdpi/icon_foreground.png
--- a/app/k9mail/src/main/res/mipmap-hdpi/icon_round.png
+++ b/app/k9mail/src/main/res/mipmap-hdpi/icon_round.png
--- a/app/k9mail/src/main/res/mipmap-mdpi/icon.png
+++ b/app/k9mail/src/main/res/mipmap-mdpi/icon.png
--- a/app/k9mail/src/main/res/mipmap-mdpi/icon_foreground.png
+++ b/app/k9mail/src/main/res/mipmap-mdpi/icon_foreground.png
--- a/app/k9mail/src/main/res/mipmap-mdpi/icon_round.png
+++ b/app/k9mail/src/main/res/mipmap-mdpi/icon_round.png
--- a/app/k9mail/src/main/res/mipmap-xhdpi/icon.png
+++ b/app/k9mail/src/main/res/mipmap-xhdpi/icon.png
--- a/app/k9mail/src/main/res/mipmap-xhdpi/icon_foreground.png
+++ b/app/k9mail/src/main/res/mipmap-xhdpi/icon_foreground.png
--- a/app/k9mail/src/main/res/mipmap-xhdpi/icon_round.png
+++ b/app/k9mail/src/main/res/mipmap-xhdpi/icon_round.png
--- a/app/k9mail/src/main/res/mipmap-xxhdpi/icon.png
+++ b/app/k9mail/src/main/res/mipmap-xxhdpi/icon.png
--- a/app/k9mail/src/main/res/mipmap-xxhdpi/icon_foreground.png
+++ b/app/k9mail/src/main/res/mipmap-xxhdpi/icon_foreground.png
--- a/app/k9mail/src/main/res/mipmap-xxhdpi/icon_round.png
+++ b/app/k9mail/src/main/res/mipmap-xxhdpi/icon_round.png
--- a/app/k9mail/src/main/res/mipmap-xxxhdpi/icon.png
+++ b/app/k9mail/src/main/res/mipmap-xxxhdpi/icon.png
--- a/app/k9mail/src/main/res/mipmap-xxxhdpi/icon_foreground.png
+++ b/app/k9mail/src/main/res/mipmap-xxxhdpi/icon_foreground.png
--- a/app/k9mail/src/main/res/mipmap-xxxhdpi/icon_round.png
+++ b/app/k9mail/src/main/res/mipmap-xxxhdpi/icon_round.png
--- a/app/k9mail/src/main/res/values-land/unread_widget_styles.xml
+++ b/app/k9mail/src/main/res/values-land/unread_widget_styles.xml
@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources xmlns:tools="http://schemas.android.com/tools">
+
+    <style name="UnreadWidgetContainer">
+        <item name="android:paddingTop">2dp</item>
+        <item name="android:paddingLeft">2dp</item>
+        <item name="android:paddingRight">2dp</item>
+        <item name="android:paddingBottom">0dp</item>
+        <item name="android:background">@drawable/unread_widget_background</item>
+        <item name="android:gravity">bottom|center_horizontal</item>
+    </style>
+
+    <style name="UnreadWidgetTextView">
+        <item name="android:textSize" tools:ignore="SpUsage">13dp</item>
+        <item name="android:background">@drawable/rounded_corners</item>
+        <item name="android:textColor">#ffffff</item>
+        <item name="android:shadowColor">#000000</item>
+        <item name="android:shadowRadius">2.0</item>
+        <item name="android:layout_marginBottom">0dp</item>
+    </style>
+
+</resources>
+
--- a/app/k9mail/src/main/res/values-sw600dp-land/unread_widget_styles.xml
+++ b/app/k9mail/src/main/res/values-sw600dp-land/unread_widget_styles.xml
@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <style name="UnreadWidgetTextView">
+        <item name="android:textSize">12sp</item>
+        <item name="android:textColor">#ffffff</item>
+        <item name="android:shadowColor">#000000</item>
+        <item name="android:shadowDy">1</item>
+        <item name="android:shadowRadius">4.0</item>
+        <item name="android:paddingBottom">0dp</item>
+    </style>
+
+</resources>
--- a/app/k9mail/src/main/res/values-sw600dp-port/unread_widget_styles.xml
+++ b/app/k9mail/src/main/res/values-sw600dp-port/unread_widget_styles.xml
@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <style name="UnreadWidgetContainer">
+        <item name="android:background">@null</item>
+        <item name="android:paddingTop">0dp</item>
+        <item name="android:paddingLeft">0dp</item>
+        <item name="android:paddingRight">0dp</item>
+        <item name="android:paddingBottom">0dp</item>
+        <item name="android:gravity">bottom|center_horizontal</item>
+    </style>
+
+    <style name="UnreadWidgetTextView">
+        <item name="android:textSize">13sp</item>
+        <item name="android:textColor">#ffffff</item>
+        <item name="android:shadowColor">#000000</item>
+        <item name="android:shadowDy">1</item>
+        <item name="android:shadowRadius">4.0</item>
+    </style>
+
+</resources>
--- a/app/k9mail/src/main/res/values-v31/manifest_values.xml
+++ b/app/k9mail/src/main/res/values-v31/manifest_values.xml
@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <!-- Home screen widgets should be disabled by default. They will be enabled programmatically if necessary. -->
+    <bool name="home_screen_widgets_enabled">false</bool>
+</resources>
--- a/app/k9mail/src/main/res/values/ic_launcher_background.xml
+++ b/app/k9mail/src/main/res/values/ic_launcher_background.xml
@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="ic_launcher_background">#FFFFFF</color>
+</resources>
--- a/app/k9mail/src/main/res/values/icon_background.xml
+++ b/app/k9mail/src/main/res/values/icon_background.xml
@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="icon_background">#FFFFFF</color>
+</resources>
--- a/app/k9mail/src/main/res/values/manifest_values.xml
+++ b/app/k9mail/src/main/res/values/manifest_values.xml
@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <!--
+    We'd like to disable this component by default. However, due to a bug in Android versions prior to 12, users then
+    wouldn't be able to use the home screen widget.
+    See https://android.googlesource.com/platform/frameworks/base/+/85be035336af8d83eb24980026418207c85991cb%5E%21/#F0
+    -->
+    <bool name="home_screen_widgets_enabled">true</bool>
+</resources>
--- a/app/k9mail/src/main/res/values/unread_widget_styles.xml
+++ b/app/k9mail/src/main/res/values/unread_widget_styles.xml
@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+
+    <style name="UnreadWidgetContainer">
+        <item name="android:paddingTop">0dp</item>
+        <item name="android:paddingLeft">0dp</item>
+        <item name="android:paddingRight">0dp</item>
+        <item name="android:paddingBottom">0dp</item>
+        <item name="android:background">@null</item>
+        <item name="android:gravity">center</item>
+    </style>
+
+    <style name="UnreadWidgetTextView">
+        <item name="android:textSize">12sp</item>
+        <item name="android:textColor">#ffffff</item>
+        <item name="android:shadowColor">#000000</item>
+        <item name="android:shadowDy">1</item>
+        <item name="android:shadowRadius">4.0</item>
+    </style>
+
+</resources>
+
--- a/app/k9mail/src/main/res/xml/network_security_config.xml
+++ b/app/k9mail/src/main/res/xml/network_security_config.xml
@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<network-security-config xmlns:tools="http://schemas.android.com/tools"
+    tools:ignore="InsecureBaseConfiguration,AcceptsUserCertificates">
+
+    <base-config cleartextTrafficPermitted="true">
+        <trust-anchors>
+            <certificates src="system" />
+            <certificates src="user" />
+        </trust-anchors>
+    </base-config>
+
+</network-security-config>
--- a/app/k9mail/src/main/res/xml/unread_widget_configuration.xml
+++ b/app/k9mail/src/main/res/xml/unread_widget_configuration.xml
@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="utf-8"?>
+<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <Preference
+        android:key="unread_account"
+        android:persistent="false"
+        android:singleLine="true"
+        android:summary="@string/unread_widget_account_summary"
+        android:title="@string/unread_widget_account_title" />
+
+    <CheckBoxPreference
+        android:key="unread_folder_enabled"
+        android:persistent="false"
+        android:enabled="false"
+        android:summary="@string/unread_widget_folder_enabled_summary"
+        android:title="@string/unread_widget_folder_enabled_title" />
+
+    <Preference
+        android:dependency="unread_folder_enabled"
+        android:key="unread_folder"
+        android:persistent="false"
+        android:singleLine="true"
+        android:summary="@string/unread_widget_folder_summary"
+        android:title="@string/unread_widget_folder_title" />
+</PreferenceScreen>
--- a/app/k9mail/src/main/res/xml/unread_widget_info.xml
+++ b/app/k9mail/src/main/res/xml/unread_widget_info.xml
@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
+    android:initialLayout="@layout/unread_widget_layout"
+    android:previewImage="@drawable/preview_unread_widget"
+    android:minHeight="40dp"
+    android:minWidth="40dp"
+    android:configure="com.fsck.k9.widget.unread.UnreadWidgetConfigurationActivity"
+    android:updatePeriodMillis="0">
+</appwidget-provider>
--- a/app/k9mail/src/release/java/app/k9mail/dev/ReleaseConfig.kt
+++ b/app/k9mail/src/release/java/app/k9mail/dev/ReleaseConfig.kt
@ -0,0 +1,9 @@
+package app.k9mail.dev
+
+import com.fsck.k9.backend.BackendFactory
+import org.koin.core.module.Module
+import org.koin.core.scope.Scope
+
+fun Scope.developmentBackends() = emptyMap<String, BackendFactory>()
+
+fun Module.developmentModuleAdditions() = Unit
--- a/app/k9mail/src/test/java/com/fsck/k9/AppRobolectricTest.kt
+++ b/app/k9mail/src/test/java/com/fsck/k9/AppRobolectricTest.kt
@ -0,0 +1,14 @@
+package com.fsck.k9
+
+import android.app.Application
+import org.junit.runner.RunWith
+import org.koin.test.AutoCloseKoinTest
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.annotation.Config
+
+/**
+ * A Robolectric test that creates an instance of our [Application] class [App].
+ */
+@RunWith(RobolectricTestRunner::class)
+@Config(application = App::class)
+abstract class AppRobolectricTest : AutoCloseKoinTest()
--- a/app/k9mail/src/test/java/com/fsck/k9/DependencyInjectionTest.kt
+++ b/app/k9mail/src/test/java/com/fsck/k9/DependencyInjectionTest.kt
@ -0,0 +1,55 @@
+package com.fsck.k9
+
+import android.view.ContextThemeWrapper
+import androidx.lifecycle.LifecycleOwner
+import androidx.work.WorkerParameters
+import com.fsck.k9.job.MailSyncWorker
+import com.fsck.k9.ui.R
+import com.fsck.k9.ui.changelog.ChangeLogMode
+import com.fsck.k9.ui.changelog.ChangelogViewModel
+import com.fsck.k9.ui.endtoend.AutocryptKeyTransferActivity
+import com.fsck.k9.ui.endtoend.AutocryptKeyTransferPresenter
+import com.fsck.k9.ui.folders.FolderIconProvider
+import com.fsck.k9.ui.folders.FolderNameFormatter
+import com.fsck.k9.ui.helper.SizeFormatter
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.koin.core.annotation.KoinInternalApi
+import org.koin.core.logger.PrintLogger
+import org.koin.core.parameter.parametersOf
+import org.koin.java.KoinJavaComponent
+import org.koin.test.AutoCloseKoinTest
+import org.koin.test.check.checkModules
+import org.mockito.kotlin.doReturn
+import org.mockito.kotlin.mock
+import org.openintents.openpgp.OpenPgpApiManager
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.RuntimeEnvironment
+import org.robolectric.annotation.Config
+
+@RunWith(RobolectricTestRunner::class)
+@Config(application = App::class)
+class DependencyInjectionTest : AutoCloseKoinTest() {
+    private val lifecycleOwner = mock<LifecycleOwner> {
+        on { lifecycle } doReturn mock()
+    }
+    private val autocryptTransferView = mock<AutocryptKeyTransferActivity>()
+
+    @KoinInternalApi
+    @Test
+    fun testDependencyTree() {
+        KoinJavaComponent.getKoin().setupLogger(PrintLogger())
+
+        getKoin().checkModules {
+            withParameter<OpenPgpApiManager> { lifecycleOwner }
+            withParameters<AutocryptKeyTransferPresenter> { parametersOf(lifecycleOwner, autocryptTransferView) }
+            withParameter<FolderNameFormatter> { RuntimeEnvironment.getApplication() }
+            withParameter<SizeFormatter> { RuntimeEnvironment.getApplication() }
+            withParameter<ChangelogViewModel> { ChangeLogMode.CHANGE_LOG }
+            withParameter<MailSyncWorker> { mock<WorkerParameters>() }
+            withParameter<FolderIconProvider> {
+                ContextThemeWrapper(RuntimeEnvironment.getApplication(), R.style.Theme_K9_DayNight).theme
+            }
+        }
+    }
+}
--- a/app/k9mail/src/test/java/com/fsck/k9/widget/unread/UnreadWidgetDataProviderTest.kt
+++ b/app/k9mail/src/test/java/com/fsck/k9/widget/unread/UnreadWidgetDataProviderTest.kt
@ -0,0 +1,145 @@
+package com.fsck.k9.widget.unread
+
+import android.content.Context
+import assertk.assertThat
+import assertk.assertions.isEqualTo
+import assertk.assertions.isNull
+import com.fsck.k9.Account
+import com.fsck.k9.AppRobolectricTest
+import com.fsck.k9.Preferences
+import com.fsck.k9.controller.MessageCounts
+import com.fsck.k9.controller.MessageCountsProvider
+import com.fsck.k9.mailstore.Folder
+import com.fsck.k9.mailstore.FolderRepository
+import com.fsck.k9.mailstore.FolderType
+import com.fsck.k9.search.SearchAccount
+import com.fsck.k9.ui.folders.FolderNameFormatter
+import com.fsck.k9.ui.messagelist.DefaultFolderProvider
+import org.junit.Test
+import org.mockito.kotlin.doReturn
+import org.mockito.kotlin.mock
+import org.robolectric.RuntimeEnvironment
+
+class UnreadWidgetDataProviderTest : AppRobolectricTest() {
+    private val context: Context = RuntimeEnvironment.getApplication()
+    private val account = createAccount()
+    private val preferences = createPreferences()
+    private val messageCountsProvider = createMessageCountsProvider()
+    private val defaultFolderStrategy = createDefaultFolderStrategy()
+    private val folderRepository = createFolderRepository()
+    private val folderNameFormatter = createFolderNameFormatter()
+    private val provider = UnreadWidgetDataProvider(
+        context,
+        preferences,
+        messageCountsProvider,
+        defaultFolderStrategy,
+        folderRepository,
+        folderNameFormatter
+    )
+
+    @Test
+    fun unifiedInbox() {
+        val configuration = UnreadWidgetConfiguration(
+            appWidgetId = 1,
+            accountUuid = SearchAccount.UNIFIED_INBOX,
+            folderId = null
+        )
+
+        val widgetData = provider.loadUnreadWidgetData(configuration)
+
+        with(widgetData!!) {
+            assertThat(title).isEqualTo("Unified Inbox")
+            assertThat(unreadCount).isEqualTo(SEARCH_ACCOUNT_UNREAD_COUNT)
+        }
+    }
+
+    @Test
+    fun regularAccount() {
+        val configuration = UnreadWidgetConfiguration(
+            appWidgetId = 3,
+            accountUuid = ACCOUNT_UUID,
+            folderId = null
+        )
+
+        val widgetData = provider.loadUnreadWidgetData(configuration)
+
+        with(widgetData!!) {
+            assertThat(title).isEqualTo(ACCOUNT_NAME)
+            assertThat(unreadCount).isEqualTo(ACCOUNT_UNREAD_COUNT)
+        }
+    }
+
+    @Test
+    fun folder() {
+        val configuration = UnreadWidgetConfiguration(appWidgetId = 4, accountUuid = ACCOUNT_UUID, folderId = FOLDER_ID)
+
+        val widgetData = provider.loadUnreadWidgetData(configuration)
+
+        with(widgetData!!) {
+            assertThat(title).isEqualTo("$ACCOUNT_NAME - $LOCALIZED_FOLDER_NAME")
+            assertThat(unreadCount).isEqualTo(FOLDER_UNREAD_COUNT)
+        }
+    }
+
+    @Test
+    fun nonExistentAccount_shouldReturnNull() {
+        val configuration = UnreadWidgetConfiguration(appWidgetId = 3, accountUuid = "invalid", folderId = null)
+
+        val widgetData = provider.loadUnreadWidgetData(configuration)
+
+        assertThat(widgetData).isNull()
+    }
+
+    private fun createAccount(): Account = mock {
+        on { uuid } doReturn ACCOUNT_UUID
+        on { displayName } doReturn ACCOUNT_NAME
+    }
+
+    private fun createPreferences(): Preferences = mock {
+        on { getAccount(ACCOUNT_UUID) } doReturn account
+    }
+
+    private fun createMessageCountsProvider() = object : MessageCountsProvider {
+        override fun getMessageCounts(account: Account): MessageCounts {
+            return MessageCounts(unread = ACCOUNT_UNREAD_COUNT, starred = 0)
+        }
+
+        override fun getMessageCounts(searchAccount: SearchAccount): MessageCounts {
+            return MessageCounts(unread = SEARCH_ACCOUNT_UNREAD_COUNT, starred = 0)
+        }
+
+        override fun getUnreadMessageCount(account: Account, folderId: Long): Int {
+            return FOLDER_UNREAD_COUNT
+        }
+    }
+
+    private fun createDefaultFolderStrategy(): DefaultFolderProvider = mock {
+        on { getDefaultFolder(account) } doReturn FOLDER_ID
+    }
+
+    private fun createFolderRepository(): FolderRepository {
+        return mock {
+            on { getFolder(account, FOLDER_ID) } doReturn FOLDER
+        }
+    }
+
+    private fun createFolderNameFormatter(): FolderNameFormatter = mock {
+        on { displayName(FOLDER) } doReturn LOCALIZED_FOLDER_NAME
+    }
+
+    companion object {
+        const val ACCOUNT_UUID = "00000000-0000-0000-0000-000000000000"
+        const val ACCOUNT_NAME = "Test account"
+        const val FOLDER_ID = 23L
+        const val SEARCH_ACCOUNT_UNREAD_COUNT = 1
+        const val ACCOUNT_UNREAD_COUNT = 2
+        const val FOLDER_UNREAD_COUNT = 3
+        const val LOCALIZED_FOLDER_NAME = "Posteingang"
+        val FOLDER = Folder(
+            id = FOLDER_ID,
+            name = "INBOX",
+            type = FolderType.INBOX,
+            isLocalOnly = false
+        )
+    }
+}