Retrieving a deleted email

You don't.  Yahoo can (sometimes) retrieve email that has been deleted in the last 7 days but it sounds like it's been longer than that since those emails were deleted from the trash.

Thank you.  I sure do not understand why they do not keep trashed emails for a longer period.  It is a poor service.

It's not a poor service (can't believe I just said that about Yahoo) it's your poor understanding of the service.  Most of the free email services have a finite limit on trash retention.  Gmail is 30 days.  They're trying to save disk space, I guess, and since most people put actual unwanted email in their trash. they figure it's a safe bet.

You're just using something in a way that was never intended.  They give you perfectly fine ways to do what you want, you just don't want to use those.

It is now only January 10.  The Deletions go back only a week, to January 3.  I think that stinks.

I'm done here.  Clearly you only want to whine about something you can't control and aren't interested in the simple solution.

Yes.  I don't care for something I can't control.  ATT should keep deleted emails available for at least 30 days.

You should have read and understood how AT&T's email works. Or, you should have a backup plan in place to archive your emails as long as you want.