IMAP OAuth2 MAILKIT Microsoft Authentication Failed

Question

I'm already working on mailboxes received from Microsoft with Mailkit IMAP and I've done the configuration with OAuth2 required from the office account!

my problem is that I receive the token but during the authentication I get an "Authentication failed" exception!

I assume this is because Microsoft's IMAP and OAuth2 configurations need to be enabled in Azure, I've tried enabling them but it still doesn't work .. !!

Answer 1

Hi @Credoffice Support
Thank you for posting your issue on Microsoft Q&A.

I understand that you are working on mailboxes received from Microsoft with Mailkit IMAP and you have done the configuration with OAuth2 but during the authentication you get an "Authentication failed" exception.

There is no plan for Outlook clients to support OAuth for POP and IMAP, but Outlook can connect use MAPI/HTTP (Windows clients) and EWS (Outlook for Mac).

If you're using POP/IMAP and SMTP for an Exchange Online account in Outlook, you must enable Basic authentication for these protocols (until it's permanently deprecated in October 1). To do so, disable Microsoft Entra security defaults if they're enabled.

Follow the document for more information: https://learn.microsoft.com/en-us/exchange/troubleshoot/administration/cannot-connect-mailbox-pop-imap-outlook?source=recommendations

Hope this helps. Do let us know if you have any further queries.

If this answers your query, do click `Accept Answer` and `Yes`.

Thanks,

B. Siri Chandana.