Another "connection to outgoing server" problem

[extechie96]

When I try to send an email in Thunderbird, in Win 10, I get a message saying "The message could not be sent because the connection to Outgoing server (SMTP) smtp.verizon.net was lost in the middle of the transaction."

This happened "suddenly"--a few hours earlier, I was able to send messages. I made no changes to the email setup, but I think I recall Tbird doing a "Compact Folders" operation before I started having the problem.

The problem does not lie in my settings, because another computer attached to the same router and same ISP has no problem sending emails, with the same settings.

I tried compacting folders again, but I still get the same message. And re-booting my computer does not solve the problem either.

This problem has been reported here before, but none of the proposed solutions work for me. Anyone have any experience with this, or any thoughts on solving the problem?

[DanRaisch]

What security software is running on that system?
Is it set to NOT scan outbound messages?

[extechie96]

I am running COMODO, but I have made no changes to it in the past year or more.

[LIMPET235]

Hi,
Could you elaborate a bit on exactly which COMODO you are running?
Is it just the free Firewall or Firewall & Antivirus?
Do you run a separate A/V program, such as AVAST or AVG etc.?

[extechie96]

I am running COMODO Firewall 10, no separate anti-virus program.

I don't understand how or why this could be relevant, since no changes were made top COMODO, or, in fact, any other program, between the last successful SEND and the first "Connection Lost" message. Nor did I re-boot in between.

[makaiguy]

Problems that crop up suddenly when no changes have been made at the user's end are often the result of problems at the mail server. If so, it likely will be corrected before too long.

[DanRaisch]

Are you certain that neither Thunderbird nor COMODO updated around the time this problem started?

[extechie96]

Yes. Tho they both updated a day or 2 after this started happening.

[skuddle]

Problems that crop up suddenly when no changes have been made at the user's end are often the result of problems at the mail server. If so, it likely will be corrected before too long.

I agree. I had a similar problem, it lasted for several days. It occurred after almost a year of running TB. It was caused by some crap that spectrum.net had done to their email system. I spent a lot of time trying to troubleshoot the problem, then after about 4 days I received some kind of update concerning TB. I applied it and the problem went away.