Disable Basic authentication for Outlook, EWS, RPS, POP, IMAP, and EAS protocols in Exchange Online.

Question

Hi,
we use mail.dll(limilabs) to receive and process email in .Net applications(Desktop applications). However recently we have came across some articles and our client also received some mail from Microsoft stating about Disabling Basic authentication for Outlook, EWS, RPS, POP, IMAP, and EAS protocols in Exchange Online from 1st Oct 2022. Will there be any impact on our .Net applications with this change as we use IMAP protocol and mail.dll in our code?

Answer 1

If you are using basic authentication - yes, there will be an impact.

First make sure IMAP is enabled in your organization:
https://www.limilabs.com/blog/office365-enable-imap-pop3-smtp

Use one of the OAuth 2.0 flows - password grant is the easiest, web flow most suited for web apps:

Password grant (MFA/2FA must be turned off for this account)
https://www.limilabs.com/blog/oauth2-password-grant-office365-exchange-imap-pop3-smtp

Client credential flow is now supported (since July 2022):
https://www.limilabs.com/blog/oauth2-client-credential-flow-office365-exchange-imap-pop3-smtp

Web apps:
https://www.limilabs.com/blog/oauth2-web-flow-office365-exchange-imap-pop3-smtp

Device flow for stand alone devices:
https://www.limilabs.com/blog/oauth2-device-flow-office365-exchange-imap-pop3-smtp

Desktop apps:
https://www.limilabs.com/blog/oauth2-office365-exchange-imap-pop3-smtp

Client Credential Flow support for POP/IMAP for Office365 was released just now (June 30th 2022):
https://www.microsoft.com/en-us/microsoft-365/roadmap?filters=&searchterms=70577