Email SMTP authentication being deprecated by Microsoft in September 2025

When setting up email notifications in Argo CD, it currently uses the SMPT protocol according to the [documentation](https://argo-cd.readthedocs.io/en/stable/operator-manual/notifications/services/email/).

Microsoft announced that that it will permanently [remove support for SMTP AUTH in September 2025](https://learn.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/deprecation-of-basic-authentication-exchange-online).
Will this have immediate impact on email notifications being send via Argo CD?
If yes:
- are there any plans to provide new authentication mechanisms such that email notifications keep on working?
- do we need to list it in the documentation?

Start with the email service documentation linked in the issue and the Microsoft SMTP AUTH deprecation notice. Determine whether the current notification path depends on the affected authentication method, then establish the supported authentication approach and update the documentation or implementation accordingly; the issue names no source files or tests.

Written by the indexing model from the issue text.