diff --git a/.idea/compiler.xml b/.idea/compiler.xml
index b86273d942..b589d56e9f 100644
--- a/.idea/compiler.xml
+++ b/.idea/compiler.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="CompilerConfiguration">
-    <bytecodeTargetLevel target="21" />
+    <bytecodeTargetLevel target="17" />
   </component>
 </project>
\ No newline at end of file
diff --git a/app/build.gradle b/app/build.gradle
index 78c9588e5a..11c42166b0 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -1,6 +1,7 @@
-apply plugin: 'com.android.application'
-apply plugin: 'kotlin-android'
-apply plugin: 'de.undercouch.download'
+plugins {
+    id 'com.android.application'
+    id 'de.undercouch.download'
+}
 
 def getVersionCode = { -> return 2315 }
 def getRevision = { -> return "a" }
@@ -100,11 +101,12 @@ android {
         // https://developer.android.com/studio/write/java8-support#groovy
         // sudo update-alternatives --install /usr/bin/java java /usr/local/android-studio/jbr/bin/java 1
         coreLibraryDesugaringEnabled = true
-        sourceCompatibility JavaVersion.VERSION_1_8
-        targetCompatibility JavaVersion.VERSION_1_8
     }
-    kotlinOptions {
-        jvmTarget = '1.8'
+
+    java {
+        toolchain {
+            languageVersion = JavaLanguageVersion.of(17)
+        }
     }
 
     externalNativeBuild {
@@ -177,7 +179,7 @@ android {
         release {
             debuggable = false
             minifyEnabled = true
-            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
             signingConfig = signingConfigs.release
             buildConfigField "String", "TX_URI", "\"\""
             buildConfigField "String", "GPA_URI", "\"\""
@@ -188,7 +190,7 @@ android {
             applicationIdSuffix '.debug'
             debuggable = true
             minifyEnabled = false
-            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
             buildConfigField "String", "TX_URI", localProperties.getProperty("paypal.uri", "\"\"")
             buildConfigField "String", "GPA_URI", localProperties.getProperty("gpa.uri", "\"\"")
             buildConfigField "String", "INFO_URI", localProperties.getProperty("info.uri", "\"\"")
@@ -348,42 +350,18 @@ android {
         }
     }
 
-    variantFilter { variant ->
-        def flavors = variant.flavors*.name
-        // Builds: release, debug
-        // Flavors: github, large, fdroid, play
-        if (variant.buildType.name == "debug" &&
-                (flavors.contains("amazon") ||
-                        flavors.contains("fdroid") ||
-                        flavors.contains("large") ||
-                        flavors.contains("play"))) {
-            setIgnore(true)
+    androidComponents {
+        beforeVariants(selector().all()) { variantBuilder ->
+            def flavors = variantBuilder.productFlavors.collect { it.second }
+            if (variantBuilder.buildType == "debug" &&
+                    (flavors.contains("amazon") ||
+                            flavors.contains("fdroid") ||
+                            flavors.contains("large") ||
+                            flavors.contains("play"))) {
+                variantBuilder.enable = false
+            }
         }
     }
-
-    // https://stackoverflow.com/questions/28948538/
-    applicationVariants.configureEach { variant ->
-        if (variant.buildType.name == "debug")
-            variant.buildConfigField "String", "MXTOOLBOX_URI", "\"https://mxtoolbox.com\""
-        else
-            variant.buildConfigField "String", "MXTOOLBOX_URI", "\"\""
-
-        //if (variant.getBuildType().isMinifyEnabled())
-        //    variant.assembleProvider.get().doLast {
-        //        for (file in variant.getMappingFileProvider().get().files)
-        //            if (file != null && file.exists()) {
-        //                def dir = "${rootDir}/app/schemas/mapping"
-        //                def name = "$archivesBaseName-$variant.baseName-$file.name"
-        //                def target = new File(dir, name)
-        //                if (!target.exists())
-        //                    copy {
-        //                        from file
-        //                        into dir
-        //                        rename { String fileName -> name }
-        //                    }
-        //            }
-        //    }
-    }
 }
 
 tasks.register('copyMarkdown', Copy) {
@@ -487,14 +465,6 @@ tasks.register('upload', Exec) {
             "filename=FairEmail-v1." + getVersionCode() + getRevision() + "-" + target + "-release.apk"
 }
 
-repositories {
-    google()
-    mavenCentral()
-    maven { url = "https://jitpack.io" }
-    //maven { url "https://oss.sonatype.org/content/repositories/snapshots" }
-    //maven { url "https://jakarta.oss.sonatype.org/content/repositories/snapshots/" }
-}
-
 configurations.configureEach {
     // Workaround https://issuetracker.google.com/issues/138441698
     // Support @69c481c39a17d4e1e44a4eb298bb81c48f226eef
diff --git a/app/src/amazon/AndroidManifest.xml b/app/src/amazon/AndroidManifest.xml
index 070c14acd4..80f185cad7 100644
--- a/app/src/amazon/AndroidManifest.xml
+++ b/app/src/amazon/AndroidManifest.xml
@@ -116,7 +116,6 @@
         android:backupAgent=".FairEmailBackupAgent"
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:description="@string/app_name"
-        android:extractNativeLibs="true"
         android:forceDarkAllowed="false"
         android:fullBackupContent="false"
         android:icon="@mipmap/ic_launcher"
diff --git a/app/src/debug/AndroidManifest.xml b/app/src/debug/AndroidManifest.xml
index d1e066285c..050fdb3420 100644
--- a/app/src/debug/AndroidManifest.xml
+++ b/app/src/debug/AndroidManifest.xml
@@ -125,7 +125,6 @@
         android:backupAgent=".FairEmailBackupAgent"
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:description="@string/app_name"
-        android:extractNativeLibs="true"
         android:forceDarkAllowed="false"
         android:fullBackupContent="false"
         android:icon="@mipmap/ic_launcher"
diff --git a/app/src/fdroid/AndroidManifest.xml b/app/src/fdroid/AndroidManifest.xml
index c800108306..bc3b6189ce 100644
--- a/app/src/fdroid/AndroidManifest.xml
+++ b/app/src/fdroid/AndroidManifest.xml
@@ -124,7 +124,6 @@
         android:backupAgent=".FairEmailBackupAgent"
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:description="@string/app_name"
-        android:extractNativeLibs="true"
         android:forceDarkAllowed="false"
         android:fullBackupContent="false"
         android:icon="@mipmap/ic_launcher"
diff --git a/app/src/github/AndroidManifest.xml b/app/src/github/AndroidManifest.xml
index 3d3d329711..433abd0c8f 100644
--- a/app/src/github/AndroidManifest.xml
+++ b/app/src/github/AndroidManifest.xml
@@ -124,7 +124,6 @@
         android:backupAgent=".FairEmailBackupAgent"
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:description="@string/app_name"
-        android:extractNativeLibs="true"
         android:forceDarkAllowed="false"
         android:fullBackupContent="false"
         android:icon="@mipmap/ic_launcher"
diff --git a/app/src/large/AndroidManifest.xml b/app/src/large/AndroidManifest.xml
index 3d3d329711..433abd0c8f 100644
--- a/app/src/large/AndroidManifest.xml
+++ b/app/src/large/AndroidManifest.xml
@@ -124,7 +124,6 @@
         android:backupAgent=".FairEmailBackupAgent"
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:description="@string/app_name"
-        android:extractNativeLibs="true"
         android:forceDarkAllowed="false"
         android:fullBackupContent="false"
         android:icon="@mipmap/ic_launcher"
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 3494350a74..d2139a6aa6 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -116,7 +116,6 @@
         android:backupAgent=".FairEmailBackupAgent"
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:description="@string/app_name"
-        android:extractNativeLibs="true"
         android:forceDarkAllowed="false"
         android:fullBackupContent="false"
         android:icon="@mipmap/ic_launcher"
diff --git a/app/src/main/java/androidx/recyclerview/selection/SelectionTracker.java b/app/src/main/java/androidx/recyclerview/selection/SelectionTracker.java
index 8c86d4adbc..1006e1c37e 100644
--- a/app/src/main/java/androidx/recyclerview/selection/SelectionTracker.java
+++ b/app/src/main/java/androidx/recyclerview/selection/SelectionTracker.java
@@ -672,7 +672,7 @@ public abstract class SelectionTracker<K> {
          *
          * @param toolTypes the tool types to be used
          * @return this
-         * @deprecated GestureSelection is best bound to {@link MotionEvent#TOOL_TYPE_FINGER},
+         * deprecated GestureSelection is best bound to {@link MotionEvent#TOOL_TYPE_FINGER},
          * and only that tool type. This method will be removed in a future release.
          */
         //@Deprecated
@@ -710,7 +710,7 @@ public abstract class SelectionTracker<K> {
          *
          * @param toolTypes the tool types to be used
          * @return this
-         * @deprecated PointerSelection is best bound to {@link MotionEvent#TOOL_TYPE_MOUSE},
+         * deprecated PointerSelection is best bound to {@link MotionEvent#TOOL_TYPE_MOUSE},
          * and only that tool type. This method will be removed in a future release.
          */
         //@Deprecated
diff --git a/app/src/main/java/eu/faircode/email/DnsBlockList.java b/app/src/main/java/eu/faircode/email/DnsBlockList.java
index 3573ccd28b..6f1f58e353 100644
--- a/app/src/main/java/eu/faircode/email/DnsBlockList.java
+++ b/app/src/main/java/eu/faircode/email/DnsBlockList.java
@@ -331,23 +331,6 @@ public class DnsBlockList {
         return null;
     }
 
-    static void show(Context context, String received) {
-        String host = DnsBlockList.getFromHost(MimeUtility.unfold(received));
-        if (host == null)
-            return;
-
-        if (host.startsWith("[") && host.endsWith("]"))
-            host = host.substring(1, host.length() - 1);
-
-        Uri uri = Uri.parse(BuildConfig.MXTOOLBOX_URI)
-                .buildUpon()
-                .appendPath("/SuperTool.aspx")
-                .appendQueryParameter("action", "blacklist:" + host)
-                .appendQueryParameter("run", "toolpage")
-                .build();
-        Helper.view(context, uri, true);
-    }
-
     private static class CacheEntry {
         private final long time;
         private final boolean blocked;
diff --git a/app/src/main/java/eu/faircode/email/HtmlHelper.java b/app/src/main/java/eu/faircode/email/HtmlHelper.java
index ffb09ed019..01409f5124 100644
--- a/app/src/main/java/eu/faircode/email/HtmlHelper.java
+++ b/app/src/main/java/eu/faircode/email/HtmlHelper.java
@@ -3180,17 +3180,6 @@ public class HtmlHelper {
 
                             ssb.append(" \uFFFC"); // Object replacement character
                             ssb.setSpan(new ImageSpan(d), ssb.length() - 1, ssb.length(), 0);
-
-                            if (!TextUtils.isEmpty(BuildConfig.MXTOOLBOX_URI)) {
-                                final String header = received[i];
-                                ClickableSpan click = new ClickableSpan() {
-                                    @Override
-                                    public void onClick(@NonNull View widget) {
-                                        DnsBlockList.show(widget.getContext(), header);
-                                    }
-                                };
-                                ssb.setSpan(click, ssb.length() - 1, ssb.length(), 0);
-                            }
                         }
 
                         ssb.append('\n');
diff --git a/app/src/main/java/javax/activation/ActivationDataFlavor.java b/app/src/main/java/javax/activation/ActivationDataFlavor.java
index 9e62dae742..6dd89a5e5b 100644
--- a/app/src/main/java/javax/activation/ActivationDataFlavor.java
+++ b/app/src/main/java/javax/activation/ActivationDataFlavor.java
@@ -209,7 +209,7 @@ public class ActivationDataFlavor /*extends DataFlavor*/ {
      * @param parameterName	the parameter name
      * @param parameterValue	the parameter value
      * @return			the normalized parameter value
-     * @deprecated
+     * deprecated
      */
     protected String normalizeMimeTypeParameter(String parameterName,
 						String parameterValue) {
@@ -226,7 +226,7 @@ public class ActivationDataFlavor /*extends DataFlavor*/ {
      *
      * @param mimeType	the MIME type
      * @return		the normalized MIME type
-     * @deprecated
+     * deprecated
      */
     protected String normalizeMimeType(String mimeType) {
 	return mimeType;
diff --git a/app/src/play/AndroidManifest.xml b/app/src/play/AndroidManifest.xml
index 4fd91839c0..0e3bcbf66a 100644
--- a/app/src/play/AndroidManifest.xml
+++ b/app/src/play/AndroidManifest.xml
@@ -114,7 +114,6 @@
         android:backupAgent=".FairEmailBackupAgent"
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:description="@string/app_name"
-        android:extractNativeLibs="true"
         android:forceDarkAllowed="false"
         android:fullBackupContent="false"
         android:icon="@mipmap/ic_launcher"
diff --git a/build.gradle b/build.gradle
index fa9075711e..47e2f7e882 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,28 +1,9 @@
-buildscript {
-    repositories {
-        google()
-        mavenCentral()
-        maven { url = "https://jitpack.io" }
-    }
-
-    dependencies {
-        // https://developer.android.com/studio/releases/gradle-plugin
-        classpath 'com.android.tools.build:gradle:8.13.2'
-        // https://kotlinlang.org/docs/releases.html#release-details
-        // https://mvnrepository.com/artifact/org.jetbrains.kotlin/kotlin-gradle-plugin
-        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:2.1.21"
-        classpath "org.jetbrains.kotlin:kotlin-android-extensions:2.1.21"
-        // https://plugins.gradle.org/plugin/de.undercouch.download
-        classpath "de.undercouch:gradle-download-task:5.6.0"
-    }
-}
-
-allprojects {
-    repositories {
-        google()
-        mavenCentral()
-        maven { url = "https://jitpack.io" }
-    }
+plugins {
+    // https://developer.android.com/studio/releases/gradle-plugin
+    id 'com.android.application' version '9.2.0' apply false
+    //id 'com.android.library' version '9.2.0' apply false
+    // https://plugins.gradle.org/plugin/de.undercouch.download
+    id 'de.undercouch.download' version '5.6.0' apply false
 }
 
 tasks.register('clean', Delete) {
diff --git a/colorpicker/build.gradle b/colorpicker/build.gradle
index 9a7dbf0cb3..af66c75c17 100644
--- a/colorpicker/build.gradle
+++ b/colorpicker/build.gradle
@@ -13,7 +13,7 @@ android {
 	buildTypes {
 		release {
 			minifyEnabled false
-			proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+			proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
 		}
 	}
 }
diff --git a/gradle.properties b/gradle.properties
index 69571f9d2c..590756bc91 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -20,4 +20,18 @@ android.nonTransitiveRClass=true
 android.nonFinalResIds=true
 
 # https://issuetracker.google.com/issues/332788833
-android.javaCompile.suppressSourceTargetDeprecationWarning=true
\ No newline at end of file
+android.javaCompile.suppressSourceTargetDeprecationWarning=true
+android.r8.strictFullModeForKeepRules=true
+android.r8.optimizedResourceShrinking=true
+
+#android.defaults.buildfeatures.resvalues=true
+#android.sdk.defaultTargetSdkToCompileSdkIfUnset=false
+#android.enableAppCompileTimeRClass=false
+#android.onlyEnableUnitTestForTheTestedBuildType=false
+#android.usesSdkInManifest.disallowed=false
+#android.uniquePackageNames=false
+#android.dependency.useConstraints=true
+#android.r8.strictFullModeForKeepRules=false
+#android.r8.optimizedResourceShrinking=false
+#android.builtInKotlin=false
+#android.newDsl=false
\ No newline at end of file
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 1ddd66ccfe..5419c3c7fa 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -4,5 +4,5 @@ distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
 #https://docs.gradle.org/current/userguide/gradle_wrapper.html
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.13-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.4.1-all.zip
 #distributionSha256Sum=23e7d37e9bb4f8dabb8a3ea7fdee9dd0428b9b1a71d298aefd65b11dccea220f
diff --git a/settings.gradle b/settings.gradle
index 247746043c..2c0061fbd0 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -1,3 +1,26 @@
+pluginManagement {
+    repositories {
+        google()
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
+
+plugins {
+    id 'org.gradle.toolchains.foojay-resolver-convention' version '1.0.0'
+}
+
+dependencyResolutionManagement {
+    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
+    repositories {
+        google()
+        mavenCentral()
+        maven { url = "https://jitpack.io" }
+    }
+}
+
+rootProject.name = "email"
+
 include ':app', ':colorpicker', ':openpgp-api'
 project(':colorpicker').projectDir = new File('colorpicker')
 project(':openpgp-api').projectDir = new File('openpgp-api')