I've read some of zbadger's past questions - https://support.mozilla.org/en-US/user/zbadger/questions - plus the initial posting in this question, which states sending fails for both phone and desktop (which are two totally different code bases). So it's hard to escape the possible conclusion that spectrum is being unreliable at sending email.

Further, google AI states "Using Charter/Spectrum email with Thunderbird is generally unreliable for sending mail, especially for legacy accounts (rr.com and twc.com). While receiving (POP/IMAP) often works, users frequently experience intermittent SMTP (outgoing) server errors, particularly after password changes.

More (not great examples I'm afraid) :

• https://support.mozilla.org/gl/questions/1436812
• https://support.mozilla.org/mk/questions/1415317

... So it's hard to escape the possible conclusion that spectrum is being unreliable at sending email. Further, google AI states "Using Charter/Spectrum email with Thunderbird is generally unreliable for sending mail, especially for legacy accounts (rr.com and twc.com). While receiving (POP/IMAP) often works, users frequently experience intermittent SMTP (outgoing) server errors, particularly after password changes.

That would track with my experience in the brief time I've been using Thunderbird.

I have not done any password change but I still get Thunderbird occasionally asking me to reenter the password.

Trying to send email through Spectrum with Thunderbird occasionally works -- other times Thunderbird sits at the sending screen forever before it will eventually time out (well over 5 minutes, I usually give up and click cancel after about 5 minutes, I've only seen TB actually get to time out twice and both those were times I just left it running while I did something else (such as typing here or fixing lunch) then came back to find that it had eventually timed out. While testing I found that on several occasions the email had actually been sent (and received) while TB was still showing that it was unsuccessfully trying to send.

I can't place the blame on either Spectrum or Thunderbird specifically because I don't totally trust anything that Spectrum does with the email system that they inherited from Road Runner and then fired everyone who actually knew how to maintain it, but I do know that Microsoft Live Mail (over a decade old) works when used on Spectrum so it seems that it is just the combination of Spectrum and Thunderbird that don't fit well together.

From everything I have been told, Spectrum intends to get completely out of the email business some time in the future (their tech support guy said he thought it would be within a year). I'm going to be switching to using my gmail accounts as my primary email addresses. But, of course, it takes time for everyone to really make the change so I'm sure I will need to at least keep incoming Spectrum emails probably as long as they keep their mail server running.

I’m sorry, but I don’t understand what the timeout discussion has to do with the original question about the inability to send emails out.

What happens when you TRY to send emails through Spectrum? [Your question said that sending doesn't work, but neither the question nor any of the explanations have said exactly what does happen]

My "sending does not work" first started as Thunderbird not finding the Spectrum SMTP server because Thunderbird automatically configured the wrong settings.

I changed the settings to the ones Spectrum says to use and Thunderbird would connect to the server but would fail authentication.

I changed the settings to those suggested here: a unique description for each outgoing server server name mail.twc.com port 587 connection security STARTTLS authentication Normal Password User Name full email address

Sometimes Thunderbird would send the email successfully. Sometimes Thunderbird would display the popup showing that it was sending and would just stay that way until either it timed out or I would give up and cancel it.

I eventually found that even when Thunderbird failed to complete the SMTP exchange, the email usually was actually sent -- apparently there was some problem between Spectrum and Thunderbird where Thunderbird was not receiving or not recognizing the acknowledgement from the Spectrum SMTP server.

According to some research by Wayne Mery, there are frequent problems using Thunderbird with Spectrum, especially on the legacy domains. (That information is elsewhere in this thread). My brief experience would tend to support the observation that Thunderbird and Spectrum's legacy SMTP server don't talk to each other very well even when the settings are all correct.

I don't think this is entirely a Spectrum problem and I don't think it is entirely a Thunderbird problem - but the two just don't work together very well.

No, none of my messages that I try to send through Thunderbird are going out anymore. I’ve had Spectrum for decades and it’s predecessor of course Time Warner. It’s only within the last few months that it stopped sending my emails. I don’t get a message at all. All it does is put my attempted email that I tried to send into my outbox.