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Cannot sent emails but can receive emails with Thuderbird (Office365)

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  • 0 have this problem
  • 9 views
  • Last reply by Matt

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I can receive emails but I cannot send emails with Thunderbird. When I try to send an email I get the error message: "Login to server smtp.office365.com with username info@mybusiness.com (not my real email address) failed". When I click on "Enter new password" nothing happens, the Window to enter the new password doesn't pop up just the same error message as above appears. Already tried everything I found in the forum as I see I am not the only one with this problem but nothing helped so far. Changed from OAuth2 to Normal password, deleted the OAuth and SMTP lines in Settings-Security-Saved Passwords but no difference... My system: Windows: 11 Home 10022631 Build 22631 (all updates) Thunderbird Version: 115.51 (latest version) Firewall/Antivirus: Windows Defender (all updates) 1.401.1565.0 Mail provider: Office 365 business (business email address: info@mybusiness.com) SMTP Settings: Description: name@mybusiness.com Server smtp.office365.com Port: 587 Security: STARTTLS Auth method: OAuth2 User name: name@mybusiness.com (see attachment) I hope someone can help me otherwise I have to use Outlook in which btw I can send emails and as well with my Gmail mail client so the problem is definitely with Thunderbird. Thanks for any help!

I can receive emails but I cannot send emails with Thunderbird. When I try to send an email I get the error message: "Login to server smtp.office365.com with username info@mybusiness.com (not my real email address) failed". When I click on "Enter new password" nothing happens, the Window to enter the new password doesn't pop up just the same error message as above appears. Already tried everything I found in the forum as I see I am not the only one with this problem but nothing helped so far. Changed from OAuth2 to Normal password, deleted the OAuth and SMTP lines in Settings-Security-Saved Passwords but no difference... My system: Windows: 11 Home 10022631 Build 22631 (all updates) Thunderbird Version: 115.51 (latest version) Firewall/Antivirus: Windows Defender (all updates) 1.401.1565.0 Mail provider: Office 365 business (business email address: info@mybusiness.com) SMTP Settings: Description: name@mybusiness.com Server smtp.office365.com Port: 587 Security: STARTTLS Auth method: OAuth2 User name: name@mybusiness.com (see attachment) I hope someone can help me otherwise I have to use Outlook in which btw I can send emails and as well with my Gmail mail client so the problem is definitely with Thunderbird. Thanks for any help!
Attached screenshots

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I have a feeling you are not sending with that SMTP server entry. Are there others in the list that do not use oauth?

My understanding of the oauth process is if authentication fails the whole browser window authorization process re occurs, not a prompt for a simple password, so my guess is your replies are not using the SMTP server you think they are. Most likely using the "default" rather than the one for the account you expect.

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