Issue Duplicate email messages from cloud-based email sending services

[Shanti]

Server operating system version

AlmaLinux 9.8

Plesk version and microupdate number

Plesk Obsidian v18.0.80_build1800260909.19 os_RedHat el9

Hi!
I have system-wide problem where all email users get some multiple (from 2-3 to 11) duplicate email messages. I have noticed that these are almost always from cloud-based email sending services like Amazon AWS SES or Postmark. So the recipient gets multiple message whereas the service (I also use Postmark) sees these with status Undeliverable.

I have tried with or without Plesk Email Security. Also my Grey listing checking is currently disabled. What could it be?

This is log excerpt from one such occasion:
| 2026-09-13 10:52:36 | postfix/qmgr [1332] | 96C189614A6: removed
| 2026-09-13 10:52:36 | postfix/pipe [1759012] | 96C189614A6: to=<[email protected]>, relay=plesk_virtual, delay=266, delays=132/0.01/0/134, dsn=2.0.0, status=sent (delivered via plesk_virtual service)
| 2026-09-13 10:52:36 | postfix-local [1759013] | 96C189614A6: arc-sign: stderr: PASS
| 2026-09-13 10:52:35 | postfix-local [1759013] | 96C189614A6: spam: stderr: PASS
| 2026-09-13 10:52:33 | postfix-local [1759013] | 96C189614A6: dmarc: stderr: PASS
| 2026-09-13 10:52:33 | postfix-local [1759013] | 96C189614A6: dk_check: stderr: PASS
| 2026-09-13 10:50:22 | postfix-local [1759013] | 96C189614A6: from=<010201a09a61b60d-39cddabc-25cd-4202-a8ab-2ad0ec126561-000000@awsses.3djake.com>, to=<[email protected]>, dirname=/var/qmail/mailnames
| 2026-09-13 10:50:22 | postfix/qmgr [1332] | 96C189614A6: from=<010201a09a61b60d-39cddabc-25cd-4202-a8ab-2ad0ec126561-000000@awsses.3djake.com>, size=120095, nrcpt=1 (queue active)
| 2026-09-13 10:50:22 | psa-pc-remote [822] | 96C189614A6: spf: stderr: PASS
| 2026-09-13 10:48:10 | psa-pc-remote [822] | 96C189614A6: check-quota: stderr: SKIP
| 2026-09-13 10:48:10 | psa-pc-remote [822] | 96C189614A6: py-limit-out: stderr: SKIP
| 2026-09-13 10:48:10 | psa-pc-remote [822] | 96C189614A6: py-limit-out: stderr: INFO:__main__:No SMTP AUTH and not running in sendmail context (incoming or unrestricted outgoing mail). SKIP message.
| 2026-09-13 10:48:10 | postfix/cleanup [1758816] | 96C189614A6: message-id=<010201a09a61b60d-39cddabc-25cd-4202-a8ab-2ad0ec126561-000000@eu-west-1.amazonses.com>
| 2026-09-13 10:48:10 | psa-pc-remote [822] | 96C189614A6: from=<010201a09a61b60d-39cddabc-25cd-4202-a8ab-2ad0ec126561-000000@awsses.3djake.com> to=<[email protected]>
| 2026-09-13 10:48:10 | postfix/smtpd [1758809] | 96C189614A6: client=a6-158.smtp-out.eu-west-1.amazonses.com[54.240.6.158]

 

[Sebahat.hadzhi]

Hi, @Shanti . If go through /var/log/maillog are there separate delivery entries for the same Message-ID?

 

[Shanti]

Yes, there are same Message-ID for separate delivery entries (where mail_id: and Queue-ID: will be different).