Bugzilla

I tried with 102.6.0 32 bit on my laptop.  

Still fails.  However, I do believe it is broadly related to this pre-existing bug 1335421

However, I can pass along from the console after trying to send message.  This behavior happens whether Thunderbird is started fresh or resumes after returning from sleep 

mailnews.pop3.42: SecurityError: a SecurityProtocol error occured     Pop3Client.jsm 350:18

which is after a delay followed by

mailnews.pop3.43: ConnectionRefusedError: a Network error occured   Pop3Client.jsm 350:18

I did not have time to try to capture from the server side of things though I suspect it would be similar to what was reported on that other bug report. 

So let me summarize as it has been a long time:

I am stuck on build 51.0b2 as this is the last build on which I can have the smart card active (either to decrypt a message or to sign an outgoing) and still have mail function normally. 

Something was changed after that build.  It is almost as if Thunderbird is somehow trying to use the certificate (or other keys?) on the card as an authentication method with the remote server(s).   It pretty clearly should not be doing this - certs on the card are for encrypt/decrypt and signing, not for server authentication/login.

Let me know if I can help further.

BTW, very much like the new look in 102.x  just wish I could use it :(