On my side Microsoft 365 generates NDR when I send the message to non existing email address using outlook online but does not generate NDR when sending a message to same non existing email address from thunderbird or other app sending emails through microsoft 365 SMTP server.
This sounds strange to me and I can't find a way to make it generate NDR aka bounce messages for messages submitted through SMTP.
This sounds strange to me and I can't find a way to make it generate NDR aka bounce messages for messages submitted through SMTP.
Peter Vágner
in reply to Peter Vágner • •Even after disabling backscatter protection under advanced antispam settings it's working like that.
These automatically generated messages can't be manipulated using transport rules, so I have no workaround for this issue.
ondrosik
in reply to Peter Vágner • •