A while back, I switched from Samsung's default SMS app (Samsung Messages) to Pulse SMS.
For many months, I've been using Pulse SMS to delete old SMS and MMS messages. After deleting almost all MMS messages and thousands of SMS messages, I backed up Android's SMS/MMS database using Epistolaire. Much to my surprise, the backup was over 500GB.
Given that SMS messages are tiny, I immediately knew something was wrong. So I loaded up Samsung's default SMS app, and sure enough, every one of my supposedly-deleted SMS and MMS messages are still technically on the Android device (even though thousands of them had supposedly been deleted by the Pulse SMS app).
Besides going through tens of thousands of SMS and MMS messages again, how can I remove all the supposedly-deleted SMS/MMS messages from Android without removing the thousands of messages I want to keep?
Also, how do I prevent this mess from happening in the future?