Issue Postfix: mail for postmaster@domain loops back to myself [every other works]

[KNARZ]

I have some weird problem with just the alias "postmaster@domain" any other alias or Mail account (so far I tested) has no issues.

The system is a VPS/Root Server with own Subdomain from the Hoster. This one I use to manage the Server with Plesk and so on. Kind of the generel Hostname as I have several domains on the System. So I'm not using my primary, all day used domain, for the hostname. (if this matters?!)

support@domain or whatever all works fine. Only postmaster@ is not working?!

This being said, this is the interessting part of the mail I receive while testing the postmaster@domain adresse.

Undelivered Mail Returned to Sender

Source of Mail:
The mail system
<root@<sub.hostname>> (expanded from
    <postmaster@<domain>>): mail for
    <sub.hostname> loops back to myself
Diagnostic-Code: X-Postfix; mail for <sub.hostname> loops back to myself

With "sub.hostname" I mean something like: vm10201.somehoster.tld 8443 for plesk)

I kind of suspected my change from the default DNS template from:
Original:

<domain>.    TXT    v=spf1 +a +mx +a:<sub.hostname> -all

Changed to:

<domain>.    TXT    v=spf1 +a +mx +a:<domain> -all

Mx Entry:

<domain>.    MX (10)    mail.<domain>.

All other entries are IPs or refer to <domain> - nothing else to <sub.hostname> [as in the original DNS template]

postconf -d
postfix conf:

mydestination = $myhostname, localhost.$mydomain, localhost
mydomain = <HOSTER-DOMAIN-without-the-subdomain-to-my-server>
myhostname = <sub.hostname>

Can someone help/explain my why postmaster is not working?

 

[Bitpalast]

These addresses are reserved for system use:

• anonymous@...
• drweb@...
• drweb-daemon@...
• kluser@...
• mailer-daemon@...
• mailman@...
• postmaster@...
• root@...

Do not configure mailboxes or own addresses on your domain with them. They won't work the way you expect it.

 

[KNARZ]

Thanks for the info.

But there is one thing than I don't understand.
I had a server running wit 11.5 and migrated to another server with onyx. In 11.5 postmaster@ worked fine. - any explainations to that situation?