I have 4 "SWBELL.NET" domain'd POP3 email accounts. I've owned these accounts for many years.

Beginning sometime around September/October 2020, two of the accounts began authentication

failures, due to password(the exact text appears below). The 2 remaining accounts continue to work

just fine.  All 4 of these "SWBELL.NET" accounts are *VERY* low volume.

I have deleted/regenerated 1 of the failing accounts just to ensure proper specification(s). But, the

authentication failure continues. I can post the critical specifications(inbound.att.net,995,SSL).

(outbound.att.net,465,SSL). But all 4 SWBELL.NET accounts specify identically(The Mozilla Tbird

queries the ATT email server for these definition settings, automatically).

The email client is Mozilla Thunderbird 78.6.0 32bit(current as of this writing).

The OS is MS/Win10.64(build 19042.685 also current as of this writing).

Is there something with ATT's POP3 authentication server that is/might be causing this?

And, I forget.... Using the correct password(the EXACT password used in the failing POP3 authentication),

I can gain IMAP access all day long. IMAP is how I've been accessing these 2 accounts since the failure

began.

Below, is the POP3 authentication message, copied exactly as issued.

"Sending of password for user [email scrubbed] did not succeed. Mail server inbound.att.net

responded: Server error - Please try again later". And, then answering "OK"/"X" to clear the message.