Outgoing TB mail fails--in just ONE of my accounts

[BruceARatcliffe]

I have 5 email addresses (or are they all called "accounts"?--shows what I know...) For years they all worked fine. Then, a month ago, one of them suddenly stopped sending outgoing messages. Every time I hit SEND, this Alert pops up:

An error occurred while sending mail. The mail server responded: Request failed; Mailbox unavailable. Please verify that your email address is correct in your account settings and try again.

The weird thing is that on every setting I can find (Server name, Server type, Port, etc.) the settings for the WORKING accounts are identical the the settings for the NON-WORKING account. I've tried all the steps recommended at the "Cannot send messages" help site.

[tanstaafl]

Its not clear whether the SMTP server is complaining that the recipients server says they don't exist, or whether it has a problem with the From: address you are using (different from the one associated with that account).

1) See if that error occurs if you send to a different recipient.
2) Check that the From: address you are using matches the username associated with the SMTP server that account is configured to use.

[BruceARatcliffe]

Dear TANSTAAFL, First off, when I dwelt on your name, it suddenly hit me--that acronym (There Ain't No Such Thing As A Free Lunch) was the theme for my Biology class 25 years ago, right down to being the title of the Final Exam essay my students wrote. I still have those essays; they showed quite an impressive understanding of how the world REALLY works, for high school freshmen!

But to get to the point, I have checked both 1 and 2:
Its not clear whether the SMTP server is complaining that the recipients server says they don't exist, or whether it has a problem with the From: address you are using (different from the one associated with that account).

1) See if that error occurs if you send to a different recipient.
2) Check that the From: address you are using matches the username associated with the SMTP server that account is configured to use.

And have seen nothing to help me solve my problem. As for #1, things go flawlessly when I send the letter, not to xxx@xxx.net, but to another email address of mine. For #2, the match you ask about is exact.

Any other ideas...?
Thanks,
Bruce

[tanstaafl]

See if you can configure that account to use another accounts SMTP server. If you're providing a username/password for it, usually that is only a problem if you use a SMTP server such as Gmail were you need to register the additional From: address with it (to prevent it from silently replacing the From: address with the Gmail accounts From: address).

[BruceARatcliffe]

See if you can configure that account to use another accounts SMTP server. If you're providing a username/password for it, usually that is only a problem if you use a SMTP server such as Gmail were you need to register the additional From: address with it (to prevent it from silently replacing the From: address with the Gmail accounts From: address).

I could attempt to follow your suggestion, but I have a more basic question: Since my other email accounts all work fine with the SAME SMTP server (all settings appear to be identical), how come one gives the error message I quoted above, and the others (identical settings, as far as I have been able to find), work flawlessly?

[tanstaafl]

Some SMTP servers are picky about what From: address you can use (has to match the email address associated with the login credentials). You might be using the same physical SMTP server on the same port, connection security, and authentication type, but in the wrong context.

When you originally created the account the new account wizard should have set up that correctly, but perhaps something has changed it. It rare, but I've seen threads where something like that occurred due to a configuration specific bug when upgrading the version of Thunderbird. With about 27 million users almost anything that can go wrong, however rare, is bound to happen to somebody.