If your account is blacklisted, that seems a bigger problem that thunderbird and IMAP. I suggest pursuing the error message in detail, as many have links to sites that give info on how to remove the blacklist.

Thank you…seems thunderbird didn’t like Surfshark vpn very much either. So after disconnecting from Surfshark, logging into comcast and getting imap and pop settings straightened out and getting all 4 apple products to play nicely…wow…think I can stop drinking…or slow down at least…thanks for your help…

You're welcome. Yes, slowing down is good. :)