PAStat's profile

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Thu, Jan 7, 2021 1:00 PM

cannot send emails, ESMTP not available

Just yesterday, started receiving this error on outgoing mails using Thunderbird using multiple Comcast email accounts:


An error occurred while sending mail: The mail server sent an incorrect greeting: Excessive failed authentication, ESMTP server temporarily not available.


Found multiple similar posts, but no clear fix. Thunderbird thinks they are sent. I can look in my account on a different device and they are in the sent folder, so got as far as the imap server. Can then resend from my iPad without any error. No problem with receiving



Gold Problem Solver


22.4K Messages

5 m ago

@PAStat wrote: ... Excessive failed authentication, ESMTP server temporarily not available. ...

That phrase usually means that you have a program, app, or device that is trying to send mail using an invalid UserID/password. If @ComcastSPAAbuse or another employee doesn't reply to your message here, Comcast Security Assurance should be able to help. You can reach them at 1-888-565-4329 (from Note that this is NOT one of the general customer service numbers.

The first-line reps there are sometimes not very helpful, so you may need to be persistent and keep at them until you get a satisfactory answer.


Regular Visitor


3 Messages

5 m ago

Same problem here with my outbound Thunderbird email but I don't think password/username is the issue.  Inbound service is fine but outbound, ESMTP, is sometimes blocked.  In my case, the error occurs on 3 different machines in my household (thus, not a hardware problem) and-- most significantly-- mainly just during daytime hours.  During later, presumably lower-traffic hours, I usually can sucessfully resend the same previously blocked mssgs that were retained in my Thunderbird Sent box.  Thus, I don't think an intermittent TB client (nor my computers) is the issue.  A Sys Admin friend says that in the system she maintains, that particular mssg is issued if the server is encountering overload traffic.   At Comcast support, after many hours with friendly techs and 2 support tickets, my final Tier 2 tech shut me down saying that since their webmail works, they don't support TB --not their problem.  No where to go next. Frustrating.

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