Issue is with spectrum server mail.twc.com error message sending and rec e mail. Outgoing server (SMTP) mail.twc.com failed. The server may be unavailable or is refusing SMTP connections.

There seems to be big problems going on at Spectrum/Charter/TWC. Neither mail.twc.com (TWC's email servers) or mobile.charter.net (Spectrum and Charter's servers) appear to be online right now and may have been down for some time. It does not seem to be a Thunderbird issue.

If you have time, you should contact Charter for status.

I'm looking into it and will report back later with what I find.

Thank you, please keep me informed with what you find.

I posted yesterday about this exact problem. I'm getting the same error message from Spectrum. I'm not sure when it started but It's been at least a few days. It's nice to know that I'm not the only one. Thanks to Lin for the response.

If you guys would like to follow this saga from another angle, check out Spectrum's own user forum where there are lots of complaints about the same things you're experiencing: intermittent or no connectivity with their servers. This affects all 3rd-party IMAP/POP/SMTP clients, not just Thunderbird. Their tech support say that they only support web mail.

https://community.spectrum.net/categories/email-22

I do find a couple of mentions of a possible workaround for Spectrum users (TWC not explicitly mentioned, though) that if you don't log into their web mail every so often their email account will be blocked until you then go to web mail. I haven't confirmed this yet and I don't know if it applies to TWC, but it might be worth a try.