On www.att.net deleted emails, back to mid 2016 have come back twice after being deleted

In February 2017 I returned home after being away for several months unexpectedly.  I deleted ''stale email'' from 12/2016 and earlier, approximately 3000 items.

Today I realized most of these deleted items are back again -- all those deleted emails and more were back again.

So once again I spent almost two hours because there is no "BULK" deletion, deleting old emails, 50 x at a time.

If they come back again I want to know what is wrong with ATT/Yahoo email because I have my email clients set to delete from server when deleted locally.

I also see I am not the only one, there are multiple users who have this problem and there appears to be no troubleshooting or work around being developed?  If I am wrong, please let me know