Microsoft Delays Retirement of Basic Authentication for SMTP AUTH

Microsoft has delayed the retirement of basic authentication for the SMTP AUTH client submissions protocol to 2027 or beyond. New tenants will be the first to be blocked and Microsoft will disable basic authentication for SMTP AUTH in a way that existing tenants can reenable the protocol. Eventually, we’ll get a date for final retirement sometime in 2027. These things take time!

https://office365itpros.com/2026/01/29/smtp-auth-basic-retirement/