Hi. My name is***** you for your question and the opportunity to assist.
This error is almost always caused by a corrupted email.
Sign in to your AT&T webmail: https://att.yahoo.com/
and delete everything in the spam/junk and deleted items folder.
Open Thunderbird and see if you get the same error.
Let me know the result please.
Hi. Did your email start coming in or are you still getting the error?
If you're still getting the error. Close and re-open Thunderbird and at the bottom of the T-Bird page
on the left side let me know how many emails it is trying to download.
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