Unique thread / account

app/src/main/java/eu/faircode/email/DB.java

@@ -71,7 +71,7 @@ import io.requery.android.database.sqlite.SQLiteDatabase;
 // https://developer.android.com/topic/libraries/architecture/room.html
 
 @Database(
-        version = 230,
+        version = 231,
         entities = {
                 EntityIdentity.class,
                 EntityAccount.class,
@@ -2307,6 +2307,12 @@ public abstract class DB extends RoomDatabase {
                         db.execSQL("ALTER TABLE `folder` ADD COLUMN `hide_seen` INTEGER NOT NULL DEFAULT 0");
                         db.execSQL("UPDATE `folder` SET hide = 0 WHERE unified");
                     }
+                }).addMigrations(new Migration(230, 231) {
+                    @Override
+                    public void migrate(@NonNull SupportSQLiteDatabase db) {
+                        logMigration(startVersion, endVersion);
+                        db.execSQL("UPDATE `message` SET thread = account || ':' || thread");
+                    }
                 }).addMigrations(new Migration(998, 999) {
                     @Override
                     public void migrate(@NonNull SupportSQLiteDatabase db) {

app/src/main/java/eu/faircode/email/MessageHelper.java

@@ -1548,11 +1548,11 @@ public class MessageHelper {
         if (thread == null && refs.size() > 0) {
             String ref = refs.get(0);
             if (!Objects.equals(ref, msgid))
-                thread = ref;
+                thread = account + ":" + ref;
         }
 
         if (thread == null)
-            thread = getHash() + ":" + uid;
+            thread = account + ":" + getHash() + ":" + uid;
 
         // Sent before
         for (TupleThreadInfo info : infos)