Mozilla Thunderbird - unable to send emails

[Tenekhaas]

Hi all,

 

I recently got fed up with using the Outlook 365 app because for some reason it requires me to sign in to my account every day, which is annoying on a desktop that only I have access to, so I started looking up alternatives. Since I was using Outlook to monitor 4 different mailboxes (2x Hotmail/Outlook, 2x Gmail), I do want a dedicated program instead of checking the web version for each one. Mozilla Thunderbird came up as best alternative according to many sources, and since I'm already using Firefox I thought it might be as smooth as my browsing experience. Sadly, this was not the case.

 

The issue: when trying to SEND messages from either of my Hotmail accounts, I'm first greeted by a "Sending message" dialog with a progress bar, which takes a while before spitting out an error message: "Login to server smtp.office365.com with username <redacted> failed."

 

With this error message I can choose to "Retry", "Enter New Password" or "Cancel". Hitting the retry option repeats the same process, and yields the same result. The option to enter a new password seems to do the exact same thing as the retry option, no dialog box is opened (also not in the background) to enter a new password. Clicking the cancel option gives another error message: "Sending of the message failed. Unable to authenticate to Outgoing server (SMTP). Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP).'"

 

Now, before anyone comes hollering:

• I have copied my password straight from my password manager (the same that allows me to log in through the browser), and I've tried using an "app password" from the Microsoft account settings page. Neither changes anything.
• I have also verified that my SMTP settings match those recommended by Microsoft (see below for my config). Probably tried a few outdated SMTP configs as well in the process.
• I have tried removing the accounts and re-adding them, multiple times (which is quite annoying since one of these accounts is roughly 2 decades old and has tens of thousands of messages to download after adding).
• I have tried deleting the stored passwords in Thunderbird to force it to prompt me for the password when syncing. No luck.
• I have tried updating Thunderbird. No change.
• I have ensured that POP and IMAP are enabled in Outlook account settings.
• I have ensured that Thunderbird is not blocked by Windows Defender Firewall.
• I have rebooted my computer and installed updates.
• This issue has been ongoing for at least several days now, it's not a temporary server outage on Microsoft's side.

 

Current config:

Windows 11 Home 23H2

Thunderbird 128.1.0esr (64-bit)

Account settings (as recommended by Microsoft):

• Server type: IMAP Mail Server
• Incoming mail:
  • Server name: outlook.office365.com
  • Port: 993
  • Connection security: SSL/TLS
  • Authentication method: OAuth2
  • User name: my email address
• SMTP server:
  • Server name: smtp-mail.outlook.com
  • Port: 587
  • Connection security: STARTTLS
  • Authentication method: OAuth2
  • Username: my email address

 

I'd be really grateful if anyone knows how to fix this issue - it seems impossible to me that it's an incompatibility issue between Thunderbird and one of the largest email providers on the planet so there has to be something. And unfortunately, "sending emails" is too much of a key functionality which I can't ignore when it doesn't work.

[manikyath]

35 minutes ago, Tenekhaas said:

because for some reason it requires me to sign in to my account every day

so.. instead of figuring out the authentication issue causing this, your solution was to switch to a different mail client that now also has an authentication issue.

 

i'd say get back to outlook, but clear all accounts from the app, and re-add them fresh.

 

i recall an oddity with outlook 365 where it required each credential twice, essentially making you log in and check the "remember password" checkbox twice in a row, before it would actually remember the darn password.

 

but to answer your question about what is the issue in thunderbird; re-read the latest instructions and re-verify how you have the accounts set up, it's probably some stupid detail about the exact formatting of the username. (yes, that is a thing...)

[Tenekhaas]

9 hours ago, manikyath said:

so.. instead of figuring out the authentication issue causing this, your solution was to switch to a different mail client that now also has an authentication issue.

 

i'd say get back to outlook, but clear all accounts from the app, and re-add them fresh.

 

i recall an oddity with outlook 365 where it required each credential twice, essentially making you log in and check the "remember password" checkbox twice in a row, before it would actually remember the darn password.

 

but to answer your question about what is the issue in thunderbird; re-read the latest instructions and re-verify how you have the accounts set up, it's probably some stupid detail about the exact formatting of the username. (yes, that is a thing...)

Thanks for the suggestion. I have already gone back and retried the setup instructions 4-5 times though, and it's weird that the same thing works for incoming but not outgoing messages.

 

As for Outlook, I also tried troubleshooting that one for a few weeks. Eventually I stumbled across some article that I can't find anymore stating that it had something to do with new European legislation, but nobody seemed to have full clarity on it. Believe me - I also tried searching for a solution for the Outlook issues for a long time before switching to TB. If anything, I'd prefer to try a 3rd program rather than going back to Outlook now.

[MartyS]

Try smpt.office365.com for the outgoing server.  That was what worked for me until work decided to block smtp access it and I was forced to use outlook.  I still use Thunderbird for my Gmail and a few other accounts.

[Tenekhaas]

11 hours ago, MartyS said:

Try smpt.office365.com for the outgoing server.  That was what worked for me until work decided to block smtp access it and I was forced to use outlook.  I still use Thunderbird for my Gmail and a few other accounts.

Tried it, sadly same result... Thanks for the hint though. I'm doing a clean install of my OS later this week (not related to this issue), so I've temporarily stopped looking for solutions, but I'm not sure I'll install Thunderbird again once that's done. Too bad.

[HubSwitch]

I have been having an issue with several accounts, hotmail.co.uk, hotmail.com and live.com using thunderbird. It started a few weeks ago where I too was getting password popups I too entered the password from the stored passwords which were correct, this did not work, so I simply cancelled the popup, EVENTUALLY.... having done the latter, I would start to get emails, but it was annoying, so I tried reinstalling, no change, so out of frustration I started to click, “retry” over and over and bingo... it would sign in, did this for all accounts, and the same happened to them, clicking every maybe 6 or 7 times, with 4 email accounts this gets tedious. I do remember seeing an email from Microsoft suggesting that there could be an issue in the future regarding access and security settings on their systems, as they were updating the type of security, I can't remember the email's content exactly, but it was shortly before the issue with thunderbird. I am getting fed with it, so decided to google for anyone else with this issue within the last month, and found this thread.

 

So, the only work round that works for me, is to hit the retry until it goes through for each account.

Windows 11 Pro 23H2, Thunderbird 128.1.0esr (64-bit), Dell laptop.

[HubSwitch]

After seeing another thread I saw something new, I have tried this, and it worked for me.

It is something to do with authentication and simply needs changing in the server settings due to their security update that I mentioned.

 

Scroll down the page to in the link below: Your Outlook or Hotmail password no longer works with Thunderbird and you cannot send or receive email

 

 

https://support.mozilla.org/en-US/kb/microsoft-oauth-authentication-and-thunderbird-202

 

I simply changed the auth to Oauth2

 

Thank me later!

Good luck

 

 

[Tenekhaas]

3 minutes ago, HubSwitch said:

After seeing another thread I saw something new, I have tried this, and it worked for me.

It is something to do with authentication and simply needs changing in the server settings due to their security update that I mentioned.

 

Scroll down the page to in the link below: Your Outlook or Hotmail password no longer works with Thunderbird and you cannot send or receive email

 

 

https://support.mozilla.org/en-US/kb/microsoft-oauth-authentication-and-thunderbird-202

 

I simply changed the auth to Oauth2

 

Thank me later!

Good luck

 

 

Thanks for the suggestion. Sadly for me I'm already on OAuth2 (see my config in my original post).