Just recently, I am unable to send replies or attachments from my Thunderbird email. My service is Comcast and I have verified my outgoing server settings as directed by Comcast. I also tried turning off my Norton for outgoing mail, still having the issue. Last week emailed worked fine.
Todas as respostas (1)
https://support.mozilla.org/kb/cannot-send-messages
Have you checked with Comcast whether they have a problem?