Mail delivery reports are received from a Plesk mail server if an email was sent from Outlook or Thunderbird:
PLESK_INFO: Delivery Status Notification
This message was created automatically by SMTP2Go.
----- The following addresses had successful delivery notifications -----
email@example.com (relayed to non-DSN-aware mailer)
Reporting-MTA: dns; mail.example.com
Original-Recipient: rfc822; firstname.lastname@example.org
Final-Recipient: rfc822; email@example.com
Remote-MTA: dns; mail.example.net
Diagnostic-Code: smtp; 250 Ok
PLESK_INFO: Mail Delivery System <MAILER-DAEMON@plesk.server.com>
This is the mail system at host plesk.server.com.
<firstname.lastname@example.org>: delivery via
some.mail.relay.com[203.0.113.2]:25: 250 2.0.0 2f1h289tms-1
Message accepted for delivery
How to disable them?
A delivery receipt confirms that an email was received by a recipient. Mail delivery reports are not generated by Plesk, but by mail clients like Outlook, Thunderbird, etc on a response from the recipient's mail server.
Disable mail delivery receipts in the mail client's settings:
- Add and request read receipts and delivery notifications - Outlook
- How to permanently request a "Delivery Status notification" | Thunderbird Support Forum | Mozilla Support