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

Thunderbird 115.16.0esr (64-bit) outgoing email not working

  • 5 replies
  • 1 has this problem
  • Last reply by sfhowes

more options

Current OS is Linux Mint 21.3 Cinnamon, and until October 2024 I've successfully used Thunderbird for years without issue.

I can reliably receive and view messages, but after carefully checking all IMAP & STMP server settings, remain unable to send any outgoing messages for past couple of weeks.

I do not own a mobile phone to be able to receive temporary codes or do any type of two-step authentication.

When attempting to send messages, here are the repeated error messages leading to endless loop that eventually times out:

Login to account "Microsoft" failed Login to server smtp.office365.com with username [email protected] failed.

Send Message Error Sending of the message failed. The message could not be sent because the connection to Outgoing server (SMTP) smtp.office365.com timed out. Try again.

Send Message Error Sending of the message failed. Unable to authenticate to Outgoing server (SMTP) smtp.office365.com. Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP)'.


Current Server Settings:

IMAP Mail Server outlook.office365.com Port 993 [email protected] SSL/TLS OAuth2

Default Outgoing Server (Microsoft) smtp.office365.com Port 587 [email protected] STARTTLS OAuth2

No so-called 'solutions' that are currently online have any effect. What do you suggest? Thanks!

Current OS is Linux Mint 21.3 Cinnamon, and until October 2024 I've successfully used Thunderbird for years without issue. I can reliably receive and view messages, but after carefully checking all IMAP & STMP server settings, remain unable to send any outgoing messages for past couple of weeks. I do not own a mobile phone to be able to receive temporary codes or do any type of two-step authentication. When attempting to send messages, here are the repeated error messages leading to endless loop that eventually times out: Login to account "Microsoft" failed Login to server smtp.office365.com with username [email protected] failed. Send Message Error Sending of the message failed. The message could not be sent because the connection to Outgoing server (SMTP) smtp.office365.com timed out. Try again. Send Message Error Sending of the message failed. Unable to authenticate to Outgoing server (SMTP) smtp.office365.com. Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP)'. Current Server Settings: IMAP Mail Server outlook.office365.com Port 993 [email protected] SSL/TLS OAuth2 Default Outgoing Server (Microsoft) smtp.office365.com Port 587 [email protected] STARTTLS OAuth2 No so-called 'solutions' that are currently online have any effect. What do you suggest? Thanks!

All Replies (5)

more options

What is the antivirus, and is there a VPN in use?

Helpful?

more options

Thanks, but in this case, following up those routes doesn't solve outgoing messages problem. Any other possibilities or suggestions?

Helpful?

more options

What does the authentication error look like? Post a screenshot. Remove any smtp:// and imap:// entries from Saved Passwords in Settings if there are any. Try adding the account to a new profile created from Help/Troubleshooting Info, about:profiles.

Helpful?

more options

Much appreciated, but removing 'Saved Passwords' and creating new profile didn't resolve problem. Still unable to send messages. Any fix coming in the near future? No change noted with last Thunderbird update just a few days ago, even with correct server settings and modern OAuth2 authentication clearly in place.

See uploaded image with requested screenshot of authentication error message.

Considering continued difficulty encountered by myself and others with outgoing email, is this an unresolved bug known to Mozilla that was worsened by Microsoft's Sept 16th pullback of suport for basic authentication?

https://answers.microsoft.com/en-us/outlook_com/forum/all/outlook-problems-from-september-16-2024/fe0bfac8-d0d6-4fd6-bf06-06e9aa89919a

Presumably a genuine security risk, but just trying to better understand, is it also not effectively blocking all competing third-party email apps like Thunderbird? Any insights?

Helpful?

more options

My hotmail account sends and receives correctly in TB 128/W10/11, so I can't explain why yours doesn't work. It might be a bug in the Linux version, which I can't test, or some external factor in your setup.

Helpful?

Ask a question

You must log in to your account to reply to posts. Please start a new question, if you do not have an account yet.