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How to diagnose OAuth2 authentication failures

billybob.mitchell
billybob.mitchell
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I've been a faithful Thunderbird user since the beginning - and continue to use Thunderbird with our company's Microsoft365 deployment

until Monday of this week -- when suddenly I find that my credentials are being refused.

The symptoms

I've read and tried all the fixes proposed in the article at https://support.mozilla.org/en-US/kb/microsoft-oauth-authentication-and-thunderbird-202 (restarting thunderbird after each step, naturally)

  • have authorized Thunderbird to our Microsoft365 tenant
  • created and tried registering with a new thunderbird profile
  • have set my security settings to 'accept all cookies'
  • have used the config editor to remove 'oauth2.issuer' and 'oauth2.scope' values
  • I've checked that my account in Microsoft365 has IMAP and Authenticated SMTP enabled

So, since Monday, I've been living in hell, trying to pretend that the Microsoft Outlook app for macOS is useable, but it's practically debilitating to be forced to use that piece of software.

Can somebody please point me to another possible set of steps that I can use to try and diagnose this?

I absolutely hate myself for having to ask for help on this, but I'm at my wit's end...

I've been a faithful Thunderbird user since the beginning - and continue to use Thunderbird with our company's Microsoft365 deployment until Monday of this week -- when suddenly I find that my credentials are being refused. The symptoms * XXX: Connected to outlook.office365.com * nothing in the activity viewer * no email coming in I've read and tried all the fixes proposed in the article at https://support.mozilla.org/en-US/kb/microsoft-oauth-authentication-and-thunderbird-202 (restarting thunderbird after each step, naturally) * have authorized Thunderbird to our Microsoft365 tenant * created and tried registering with a new thunderbird profile * have set my security settings to 'accept all cookies' * have used the config editor to remove 'oauth2.issuer' and 'oauth2.scope' values * I've checked that my account in Microsoft365 has IMAP and Authenticated SMTP enabled So, since Monday, I've been living in hell, trying to pretend that the Microsoft Outlook app for macOS is useable, but it's practically debilitating to be forced to use that piece of software. Can somebody please point me to another possible set of steps that I can use to try and diagnose this? I ''absolutely hate myself'' for having to ask for help on this, but I'm at my wit's end...

All Replies (2)

billybob.mitchell
billybob.mitchell Question owner
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I should have added, these are the parameters I'm using to connect to Microsoft365 mail:

IMAP: Server name: outlook.office365.com Port: 993 Encryption method: TLS

SMTP: Server name: smtp.office365.com Port: 587 Encryption method: STARTTLS

I've tried using an app password that I had created with the 'Encrypted password' setting, as well as the OAuth authentication method.

Roland Tanglao
Roland Tanglao
  • Moderator
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Hi billybob.mitchell

Please try troubleshoot mode (if you haven't already): https://support.mozilla.org/en-US/kb/troubleshoot-mode-thunderbird

If that doesn't help: Please provide the following troubleshooting details to help us help you:

  1. let us know your email provider (unlikely to cause the problem but stranger things have happened) e.g. are you using outlook.com, hotmail.com or email on your domain e.g. email on a godaddy domain that uses Microsoft 365, etc
  2. let us know what operating system e.g. macOS Ventura,
  3. let us know what 3rd party software like add-ons, anti-virus or firewalls you are using (and please try disabling them and see if that helps)

Cheers! ...Roland