Basic Auth Re-enablement / OAuth Opt-Out

It is recommended to enable and leverage OAuth for Microsoft Exchange over Basic Authentication which is our current implementation.

However, if your tenancy/environment is not ready or not able to activate, please follow the instructions below to opt-out of OAuth and re-enable Basic Auth.

IMPORTANT: All customers will be able to use the self-service diagnostic to re-enable basic auth for any protocols they need, once per protocol.

  • To invoke the self-service diagnostic, you can go directly to the basic auth self-help diagnostic by simply clicking on this button (it’ll bring up the diagnostic in the Microsoft 365 admin center if you’re a tenant Global Admin)

  • Or you can open the Microsoft 365 admin center and click the green Help & support button in the lower right-hand corner of the screen.

  • When you click the button, you enter our self-help system. Here you can enter the phrase “Diag: Enable Basic Auth in EXO

Opting Out of OAuth

  • The diagnostic will show a version of the dialog below, and you can re-run it for multiple protocols. It might look a bit different if some protocols have already been disabled. Note too that protocols are not removed from the list as you opt-out but rest assured (unless you receive an error) we will receive the request.


Re-Enabling Basic Auth

  • The diagnostic can not be used to re-enable basic auth (it is in opt-out only mode).

    • If you require one of the protocols to be re-enabled for basic auth during the month of September, please open a support ticket with Microsoft.

    • IMPORTANT: You can re-enable basic auth for SMTP Auth by yourself and follow best practices; see this article.


  • Once you run the diagnostics and ask us to re-enable basic for a protocol, basic auth will start to work again.

Go to the link below to learn more:

Basic Authentication Deprecation in Exchange Online

Timeline Summary:




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