I have an account with Network Solutions that I've been using for about 20 years with minimal issues. I download messages to Thunderbird via POP and send messages via SMTP. NS just upgraded their email system. The POP3, IMAP and SMTP servers are all new, with new names. I updated to the server settings in Thunderbird and POP still works fine, but I get the attached error when attempting to send a message via SMTP. I just now upgraded TB to 102.3.3 and still get the send error. The strange thing is that using those exact same server config settings on my iPhone and iPad, I can send and receive with no issues. Is there a log file somewhere in Thunderbird that would provide any more information about this error? Anyone have any ideas what the problem might be? Thank you