Can't add Office365 account (Authentication Error - Check your username and password. (SMTP))

Bug Reports
23

We were going to buy a bunch of licenses for work to eventually replace OUtlook but we can’t get passed the Office/Microsoft 365 login loop and failed authentication errors. I guess we’ll be staying on Outlook until we can find yet another mail client that actually works.

24

This is still a problem. If you cannot change things server side - and with universities or companies you cannot - this problem is unsolvable without support from Mailspring. I have not been able to find any at all. For me, that means that Mailspring is of no use to me. Pity.

1 Like
25

It’s July 2024 and this is still an issue for O365 mail, even with the authenticated SMTP selected (which is not ideal). Shame as getting this working was the last thing preventing me from going for the paid version. Hopefully this will finally be resolved.

26

Any way to fix this issue by changing the code and building the app on windows? How to fix this without using the SMTP authentication?

27

If your M365/Office365 tenant (Education/Corporate) doesn’t have IMAP and SMTP enabled, there’s not much you can do. This client doesn’t support native Exchange, EWS, or ActiveSync sadly…

1 Like
28

This problem is now happenning for outlook not Office365

29

Hey folks, thanks for all the reports and discussion around this. Mailspring 1.20.0 (released today) adds detailed Office 365 / Outlook account setup guidance and troubleshooting documentation accessible from the account setup screen.

Alex is correct that if your If your M365/Office365 tenant (Education/Corporate) doesn’t have IMAP and SMTP enabled, you may not be able to connect your account. Conditional Access policies or MFA configurations that block third-party apps entirely can also block setup (this is a Microsoft admin setting, not something we can work around on our end unfortunately).

Hope the new documentation and setup instructions help make this process a bit smoother.

30

Office 365 account setup guidance was improved in v1.20.0 with updated documentation and prompts. The key things for O365 accounts:

  1. Use OAuth (recommended): In account setup, select “Office 365 / Outlook” and complete the OAuth flow — this is the most reliable method
  2. Enable IMAP: Make sure that you’ve enabled IMAP and SMTP in your Outlook settings. If you don’t see the SMTP option, Outlook may be entirely blocking you from using third-party email clients to send mail.

Note: Microsoft has deprecated basic authentication for Exchange, so OAuth is the preferred path going forward.