These kinds of errors are appearing with roadrunner/TWC/Spectrum/Charter accounts. Check that you have the correct server settings:

https://support.mozilla.org/en-US/questions/1275339#answer-1275322

https://support.mozilla.org/en-US/questions/1274609#answer-1274779

IMAP Server name: mobile.charter.net Port: 993 Connection security: SSL/TLS Authentication: Normal Password

SMTP Server name: mobile.charter.net Port: 587 Authentication: Normal password Connection security: STARTTLS Spectrum says that is correct. Also tried SSL/TLS

Changing from mail.twc.com to mobile.charter.net eliminated the failed response: ID message.

However, can not log in as password is rejected. Same password I use to log in via webmail.

For the outgoing, set the security as SSL/TLS and then type in port 587. The usual security on 587 is STARTTLS, but not in this case:

https://support.mozilla.org/en-US/questions/1234783#answer-1157069

Delete the passwords in Options/Security/Passwords/Saved Passwords, restart TB, and enter the correct ones when prompted. Plus, always disable antivirus scanning of outgoing mail.

Password was not in Saved Passwords. Put it there. Can not log in.

Checked Windows Defender, can not find where to check scanning of outbound mail. Turned off Defender and tried to log in to email account. can not log in.

Excluded TB Profile folder from scanning by Windows Defender. Can not log in.

This Community Support feature is nice. I am getting help but, not solving problem. Any more suggestions?