Microsoft 365 · SMTP AUTH
What is happening to SMTP AUTH Basic Authentication?
Microsoft is changing the default handling of username/password SMTP AUTH. It is not removing SMTP itself. The final removal date for Basic Authentication has not been announced.
Microsoft source · Last technically verified · Original documentation ↗
Current Microsoft schedule
Separate a default change from final removal.
The schedule has changed before; verify the Microsoft announcement during migration planning.
Behavior remains unchanged
Existing tenants keep the current SMTP AUTH Basic Authentication behavior.
Disabled by default
Administrators can still enable Basic Authentication for SMTP AUTH in existing tenants when needed.
Microsoft to announce a final removal date
There is no announced final removal date to put in a countdown. Plan a supported alternative rather than treating the default-change date as a hard shutdown.
What to change
Match the solution to the sender’s actual capabilities.
Can it use OAuth?
Use modern client SMTP submission directly when the device or application supports it.
Can your network use Microsoft relay?
A connector, certificate or static IP and port 25 may avoid a local bridge.
Does it rely on password-based SMTP AUTH?
Use an appropriate bridge or server only if the sender must remain on SMTP and Microsoft 365 remains the outbound tenant.