On October 1, 2022, Microsoft will start to randomly select tenants and disable basic authentication access for several Exchange Online protocols, including MAPI, POP, IMAP and more. Microsoft promises that SMTP authentication will not be affected, however our preliminary tests do not prove that.
How does this affect me?
If you use Recovery Manager for Active Directory Disaster Recovery including Standard and Forest Editions email notifications with Exchange Online as a SMTP server (a "smtp.office365.com" server is configured in Recovery Manager for Active Directory email notifications settings), email notifications might stop working on October 1, 2022.
Microsoft is offering a one-time basic authentication re-enablement for specific protocols. We recommend following steps from this Microsoft article. Basic Authentication Deprecation in Exchange Online and request a one-time SMTP basic authentication re-enablement.
The Recovery Manager for Active Directory team is developing a resolution and targeting a Q4 release.We apologize for the inconvenience this issue may have caused and we are working quickly to correct it.