Where have all the males (emails) gone, long time passing

People of great knowledge, and dummies too.
My deleted emails are disappearing…they are truly deleting which is good unless I’d like to reread one!.
Where oh where could they be going…not in the Deleted or Trash folder??.
The same thing is happening if I use Outlook but not if I use Yahoo Mail.

Please help, my sanity depends on it.