Question Unable to handle email bounce back of spoof email with sender and receiver the same

[nisamudeen97]

Server operating system version

Almal Linux 8

Plesk version and microupdate number

Obsidian 18.0.70 Update #2

Hi,

Few of our email accounts in our Plesk Obsidian 18.0.70 linux system with AlmaLinux 8.10 is getting strange bounce back emails. See the screen shot attached. We are getting this at random intervals. For outgoing emails we are using Safe-route relay server. I have checked this in detail and below are my findings.

• Spoofed emails are getting rejected as per SPF failure.
• As the sender and receiver are the same email, a bounce back email is generated from the server.
• The sender of the bounce back is "mailer-demon", so DMARC will not be applied.
• As the domain is on the same server, Plesk delivers it directly without sending to Safe-route relay

How we can handle this situation of sender and receiver the same spoof emails on an out going SMTP relay plesk.