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Thunderbird was sending emails, then suddenly it stopped doing so

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Hi --

I was able to send emails from Thunderbird, then suddenly I couldn't. I get a message that the login with my username failed. I have no problem receiving emails, and the same password is used for sending and receiving.

After a notice that the login failed, I get this notice: "Unexpected error 80004005." I can't find any information on that error.

I tried everything on https://support.mozilla.org/en-US/kb/cannot-send-messages. (I verified SMTP settings and SMTP server; I tried shutting down firewall and antivirus; surely, Microsoft office for enterprises has a minimum version of TLS; I set a new password.

I use Thunderbird with a MIT alum account -- a Microsoft enterprise account. (This is not a situation where an alum account forwards email to another mail provider; MIT has a Microsoft enterprise account for alums.)

I use Kaspersky "total security." Version number is 21.2.16.590 (c).

Operating system is Windows 10 (I always update).

Thunderbird version is 78.8.1 (32 bit).

I've attached screen shots of my account settings and SMTP settings.

Let me know if you need anything more.

Thanks! Jonathan

Hi -- I was able to send emails from Thunderbird, then suddenly I couldn't. I get a message that the login with my username failed. I have no problem receiving emails, and the same password is used for sending and receiving. After a notice that the login failed, I get this notice: "Unexpected error 80004005." I can't find any information on that error. I tried everything on https://support.mozilla.org/en-US/kb/cannot-send-messages. (I verified SMTP settings and SMTP server; I tried shutting down firewall and antivirus; surely, Microsoft office for enterprises has a minimum version of TLS; I set a new password. I use Thunderbird with a MIT alum account -- a Microsoft enterprise account. (This is not a situation where an alum account forwards email to another mail provider; MIT has a Microsoft enterprise account for alums.) I use Kaspersky "total security." Version number is 21.2.16.590 (c). Operating system is Windows 10 (I always update). Thunderbird version is 78.8.1 (32 bit). I've attached screen shots of my account settings and SMTP settings. Let me know if you need anything more. Thanks! Jonathan
Attached screenshots

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Finally, the problem was some security fix the folks who run email at MIT had implemented. They were able resolve the matter so I can send email... Boy, was that not easy! But the problem had nothing to do with Mozilla or Thunderbird. In any event, thanks for your help!

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All Replies (8)

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'Shutting down' AV may not be sufficient to test if it's a source of the problem. Run in Windows safe mode (to bypass startup apps like AV) and then test TB. If you changed the password, remove the old ones from Saved Passwords in Options, restart TB, enter the new one when prompted.

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Thanks for writing, but I tried both of those suggestions -- got rid of lots of old passwords and started twice in safe mode -- and neither worked.

Any other ideas? Should I try reinstalling Tbird? Perhaps installing the most recent past version?

-- Jonathan

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Since this appears to be an O365 account, try setting the authentication to OAuth2 for incoming and outgoing, remove the passwords, restart TB, and see if you can enter the account password in the OAuth browser window that will appear (if the account works with OAuth2). This wouldn't work with an outlook.com consumer address, but it might with your enterprise account.

Uninstalling/reinstalling seldom fixes issues like this, as the relevant data is in the separate profile folder.

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Oh dear. The OAuth2 worked fine for incoming emails, but still no luck with sending.

Just to double check, I'm using SSL/TLS security on the server for incoming emails (outlook.office365.com) and STARTTLS for outgoing (smtp.office365.com) -- you don't see any problems there?

Thanks again!

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STARTTLS on 587 for smtp.office365.com is correct, but I think you may have to ask the mail administrator to change some settings. See this topic for some suggestions. It's never a straightforward operation to configure O365 accounts in TB.

Another option: https://support.mozilla.org/en-US/questions/1288493

Modified by sfhowes

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I appreciate your help!

I'll check the options you suggest, as well as check with tech support for the email.

-- Jonathan

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Chosen Solution

Finally, the problem was some security fix the folks who run email at MIT had implemented. They were able resolve the matter so I can send email... Boy, was that not easy! But the problem had nothing to do with Mozilla or Thunderbird. In any event, thanks for your help!

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@Jonathan, Can you share the solution? I am also a MIT alum with the same SMTP issue. Thanks! - David