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

  • 3 replies
  • 2 have this problem
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  • Last reply by Matt

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For a month now one of my 4 email addresses has given the famous error message that gets a lot of play on these pages:

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 other ones work fine, except for my (my name)@sbcglobal.net, which, when I try to send from returns this error message:

Login to server outbound.att.net with username (my name)@sbcglobal.net failed.

It is worth noting that 3 of my email addresses work fine, so the above error message is not the root problem (?)

I tried removing the REPLY TO entry, and putting in the same email address in that box as the email I was sending from. These solutions worked for some people, but make no difference for me. Any other things to try? Thanks for any suggestions.

For a month now one of my 4 email addresses has given the famous error message that gets a lot of play on these pages: 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 other ones work fine, except for my (my name)@sbcglobal.net, which, when I try to send from returns this error message: Login to server outbound.att.net with username (my name)@sbcglobal.net failed. It is worth noting that 3 of my email addresses work fine, so the above error message is not the root problem (?) I tried removing the REPLY TO entry, and putting in the same email address in that box as the email I was sending from. These solutions worked for some people, but make no difference for me. Any other things to try? Thanks for any suggestions.

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Info:

The first link mentions a security upgrade is coming to AT&T email. I'm presuming the account in Thunderbird is a pop mail account based on the outgoing server info you supplied.

If yes, then according to info you will need to create and use a secure mail key. You’ll use this secure mail key instead of your AT&T password.

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I am having the same problem, but I'm not with AT&T, I'm with Yahoo. Any help would be appreciated!

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his conversation is would appear continues here https://support.mozilla.org/en-US/questions/1275119