Yesterday, 07:38 AM
So, that only happens to messages that you put in Mail's trash?
That's usually because you don't need to keep them, correct?
Deleted messages go in the trash.
Sounds like your trash is just too automatic for your purposes.
If you want to be sure about keeping your messages, then don't put them in the trash :D (Don't delete your messages, if you really want to save them… )
Make a folder in your account - maybe more than one if you have multiple interests, and drag your messages to the folder of your choice.
That extra folder will keep your messages fully under your control.