diff --git a/android/app/src/main/AndroidManifest.xml b/android/app/src/main/AndroidManifest.xml
index 30262e95..c6647b77 100644
--- a/android/app/src/main/AndroidManifest.xml
+++ b/android/app/src/main/AndroidManifest.xml
@@ -13,7 +13,7 @@
       <data android:scheme="https"/>
     </intent>
   </queries>
-  <application android:name=".MainApplication" android:label="@string/app_name" android:icon="@mipmap/ic_launcher" android:roundIcon="@mipmap/ic_launcher_round" android:allowBackup="true" android:theme="@style/AppTheme" android:supportsRtl="true" android:enableOnBackInvokedCallback="false" android:fullBackupContent="@xml/secure_store_backup_rules" android:dataExtractionRules="@xml/secure_store_data_extraction_rules">
+  <application android:name=".MainApplication" android:label="@string/app_name" android:icon="@mipmap/ic_launcher" android:roundIcon="@mipmap/ic_launcher_round" android:allowBackup="false" android:theme="@style/AppTheme" android:supportsRtl="true" android:enableOnBackInvokedCallback="false" android:fullBackupContent="@xml/secure_store_backup_rules" android:dataExtractionRules="@xml/secure_store_data_extraction_rules">
     <meta-data android:name="expo.modules.updates.ENABLED" android:value="false"/>
     <meta-data android:name="expo.modules.updates.EXPO_UPDATES_CHECK_ON_LAUNCH" android:value="ALWAYS"/>
     <meta-data android:name="expo.modules.updates.EXPO_UPDATES_LAUNCH_WAIT_MS" android:value="0"/>
diff --git a/app.config.js b/app.config.js
index e228b2b0..ceb0fb41 100644
--- a/app.config.js
+++ b/app.config.js
@@ -56,6 +56,11 @@ module.exports = {
       edgeToEdgeEnabled: true,
       predictiveBackGestureEnabled: false,
       package: 'com.anonymous.bulwarkmobile',
+      // The AsyncStorage database holds cached message bodies, the outbox and
+      // the account registry; the platform backup would ship all of it to the
+      // user's Google account. Credentials live in SecureStore (excluded by
+      // its own rules) but the mail cache must not leave the device either.
+      allowBackup: false,
     },
     web: {
       favicon: './assets/favicon.png',