Microsoft is proactively working on securing their Exchange Online environment. Making your and indirectly other customers environments safer. For now Microsoft is going over all tenants and they will start disabling Basic Authentication. This will include all of the following services: Exchange Web Services (EWS), Exchange ActiveSync (EAS), POP, IMAP, Remote PowerShell, MAPI, RPC, SMTP AUTH and OAB. Microsoft will start disabling basic authentication permanently beginning October 1, 2022. So if you still have applications that cannot work with modern authentication, it is 5 to 12, make sure they can quickly.
Early 2022 Microsoft will selectively pick tenants and disable Basic Auth for all affected protocols except SMTP AUTH for a period of 12-48 hours. After this time, Basic Auth for these protocols will be re-enabled.
During this time all clients and apps that use Basic Auth in the selected tenants will be affected, and they will be unable to connect. Any client or app using Modern Authentication will not be affected. Users can switch to other clients (for example, use Outlook on the Web instead of an older Outlook client that does not support Modern Authentication) while they upgrade or reconfigure their client apps.
You can now go directly to the Basic Auth self-help diagnostic by simply clicking on this link: Enable Basic Auth in EXO (it’ll bring up the diagnostic in the Microsoft 365 admin center if you’re the tenant admin). Or you can open the Microsoft 365 admin center and click the green Help and support button in the lower right hand corner of the screen.
When you click the button, you enter the self-help system. Here you can enter the magic phrase “Diag: Enable Basic Auth in EXO”
Once you submit your opt out request, Microsoft won’t disable Basic Auth for the selected protocol(s) in your tenant, whether there is usage or not, until October 2022. Every tenant can request an opt out for each protocol (or set of protocols in the case of Outlook), until the start of September 2022. Starting September 1, 2022, Microsoft will remove the opt out option, and starting October 1, 2022, they will begin turning off Basic Auth in all tenants, regardless of usage.