Office 365 Deprecation of Basic Authentication
Sep 10, 2025
Overview
https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/deprecation-of-basic-authentication-exchange-online
Solution
However, please note that, per Microsoft's documentation, "SMTP AUTH will still be available when Basic authentication is permanently disabled on October 1, 2022. The reason SMTP will still be available is that many multi-function devices such as printers and scanners can't be updated to use modern authentication.", please see this doc:
https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/deprecation-of-basic-authentication-exchange-online#impact-to-messaging-protocols-and-existing-applications
