This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

I can't send emails any more, since yesterday. I get an error message saying, in part "... Requested action not taken: mailbox unavailable Failure sending mail

  • 3 cavab
  • 1 has this problem
  • 3 views
  • Last reply by sfhowes

more options

I can't send emails any more, since yesterday. I get an error message saying, "An error occurred while sending mail. The mail server responded: Requested action not taken: mailbox unavailable. Failure sending mail. Try again later. Please check the message recipient "xxxxxxxxxxx@mail.com" and try again"

Interestingly, if I select another email address (gmail in this case) as the sender, it sends OK.

Edit: This has proved to be an intermittent problem! Sometimes I can send test emails to myself, sometimes I can't.

Mail provider: mail.com ISP: ??? USB or wireless tether to mobile phone. Anti-virus: Windows Firewall Windows version: Windows 7 Professional ©2009 Thunderbird 52.9.1 (32-bit)

I can't send emails any more, since yesterday. I get an error message saying, "An error occurred while sending mail. The mail server responded: Requested action not taken: mailbox unavailable. Failure sending mail. Try again later. Please check the message recipient "xxxxxxxxxxx@mail.com" and try again" Interestingly, if I select another email address (gmail in this case) as the sender, it sends OK. Edit: This has proved to be an intermittent problem! Sometimes I can send test emails to myself, sometimes I can't. Mail provider: mail.com ISP: ??? USB or wireless tether to mobile phone. Anti-virus: Windows Firewall Windows version: Windows 7 Professional ©2009 Thunderbird 52.9.1 (32-bit)
Attached screenshots

Modified by IanStar

All Replies (3)

more options
more options

Tried the troubleshooter options above, to no avail. Mail.com suggests it's the SMTP setting in Thunderbird which is causing the (intermittent) problem, and that I should upgrade to Premium.

more options

According to their website, the smtp settings (for Premium accounts) are smtp.mail.com on port 587, Connection security = none, authentication = password, transmitted insecurely, User name = email address. But another page recommends: smtp.mail.com on port 465, SSL/TLS security, normal password authentication. And yet a third source suggests smtp.mail.com on port 587, STARTTLS security, normal password authentication.

There's no indication their non-Premium service supports mail access with 3rd-party programs like TB. That would explain a 'mailbox unavailable' error.