I know nothing of code 1014, but if you share more information, such as email provider, incoming and outgoing server names, ports, authentication settings, that may provide some insight. From your note, it seems that your email works okay sometimes, and sometimes not.

It's been happening for weeks that I can get my IMAP and then sometimes not my SMTP. Comcast is my ISP. My husband put in Thunderbird mail years ago, and he died May 2020. I'm doing my best to learn about this, and sometimes things work. I've learned about IMAP and SMTP and port numbers and I've called comcast yesterday and they couldn't help. I did get advice recently to remove the Thunderbird mail and then reinstall it, and that's what I tried and today I'm getting my IMAP mail. Every time this happens I get a code 1014 that says I can't connect to mail.comcast.net and I don't know why. I really appreciate you reaching out to me. I prefer your email to another. Thank you. Barbara

Okay, for starters, what is your incoming server and port, the outgoing server and port? What is the full error message you receive? And do you have problems if you use the comcast website for access?

Okay, while you're gathering info, I've been thinking. You should NOT (in my opinion) be attempting to access mail.comcast.net, so I"m wondering if you have email account set to that (?) And you mentioned that you receive mail but get error that you cannot connect to mail.comcast.net. Are you saying that you receive mail ,but cannot send mail? I cannot say what is or is not the proper setup, but my web search indicates the following:

   Incoming Mail Server Name: imap.comcast.net
   Incoming Mail Server Port Number: 993 with SSL ON
   If the Mail Client lets you select an authentication method, choose STARTTLS.
       If Needed: 143 with SSL ON
   Outgoing Mail Server Name: smtp.comcast.net
   Outgoing Mail Server Port Number: 587 (SMTP)
       If Needed: 465 (SMTPS)
   Encryption: TLS (use SSL if TLS isn't shown.)
   Authentication: Type in your Comcast username and password

Does this reflect your settings, Barbara?

This may appear twice. My regrets. Sometimes I respond and a moderator wants to approve - which is fine - but sometimes it takes so many hours that the conversation is lost. So, I'll try to duplicate it and not involve moderator:

You mention getting an error when attempting to contact mail dot comcast dot net - but I don't think that is the appropriate server. Here are the settings I found. Let me know if they mirror yours:

   Incoming Mail Server Name: imap dot comcast dot net
   Incoming Mail Server Port Number: 993 with SSL ON
   If the Mail Client lets you select an authentication method, choose STARTTLS.
       If Needed: 143 with SSL ON
   Outgoing Mail Server Name: smtp dot comcast dot net
   Outgoing Mail Server Port Number: 587 (SMTP)
       If Needed: 465 (SMTPS)
   Encryption: TLS (use SSL if TLS isn't shown.)
   Authentication: Type in your Comcast username and password

If your settings are different, we may be close, Barbara. Otherwise, we're still digging.