Added hint text

app/src/main/res/layout/fragment_folder.xml

@@ -292,6 +292,18 @@
             app:layout_constraintStart_toStartOf="parent"
             app:layout_constraintTop_toBottomOf="@id/cbKeepAll" />
 
+        <eu.faircode.email.FixedTextView
+            android:id="@+id/tvAutoDeleteHint"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="6dp"
+            android:text="@string/title_auto_delete_hint"
+            android:textAppearance="@style/TextAppearance.AppCompat.Small"
+            android:textStyle="italic"
+            app:layout_constraintEnd_toStartOf="@+id/btnInfo"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/cbAutoDelete" />
+
         <Button
             android:id="@+id/btnSave"
             android:layout_width="wrap_content"
@@ -300,7 +312,7 @@
             android:tag="disable"
             android:text="@string/title_save"
             app:layout_constraintStart_toStartOf="parent"
-            app:layout_constraintTop_toBottomOf="@id/cbAutoDelete" />
+            app:layout_constraintTop_toBottomOf="@id/tvAutoDeleteHint" />
 
         <eu.faircode.email.ContentLoadingProgressBar
             android:id="@+id/pbSave"

app/src/main/res/values/strings.xml

@@ -665,6 +665,7 @@
     <string name="title_keep_all">Keep all messages</string>
     <string name="title_auto_trash">Automatically move old messages to trash</string>
     <string name="title_auto_delete">Automatically permanently delete old messages</string>
+    <string name="title_auto_delete_hint">Old messages are messages that are no longer kept on the device</string>
     <string name="title_folder_name_missing">Folder name missing</string>
     <string name="title_folder_exists">Folder %1$s exists</string>
     <string name="title_folder_delete">Permanently delete this folder and any messages it contains?</string>