Issue Relay access denied for root mails

[fliegerhermi]

Server operating system version

Ubuntu 24.04.1 LTS

Plesk version and microupdate number

Plesk Obsidian 18.0.66 Update 2

Hi. I have a brand new plesk server on Ubuntu 24.
Root Mails are configured to be sent to an external address through /etc/aliases.

However when "monit" tries to send me mails, I get the follow maillog message:

Jan 13 20:11:11 web10 postfix/smtpd[13406]: connect from localhost.localdomain[::1]
Jan 13 20:11:11 web10 postfix/smtpd[13406]: NOQUEUE: reject: RCPT from localhost.localdomain[::1]: 454 4.7.1 <[email protected]>: Relay access denied; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<web10.XXXX.de>
Jan 13 20:11:11 web10 psa-pc-remote[7732]: Message aborted.
Jan 13 20:11:11 web10 psa-pc-remote[7732]: Message aborted.
Jan 13 20:11:11 web10 postfix/smtpd[13406]: disconnect from localhost.localdomain[::1] ehlo=1 mail=1 rcpt=0/1 quit=1 commands=3/4

I noticed that the mynetworks= config field is empty in the main.cf
Usually localhost should be permitted, because it is in mynetworks. I noticed that another server is working with the exact same main.cf, but ipv6 is not enabled on the other node.
How can I resolve this issue? Is it save to setup the mynetworks field or does that screw up something like outgoing mail limit?

Thank you for your help

 

[scsa20]

Assuming this is all being done locally you can can go to Tools & Settings > Mail Server Settings > White List and add 127.0.0.1/32 if it's not already in there.

 

[mow]

Assuming this is all being done locally you can can go to Tools & Settings > Mail Server Settings > White List and add 127.0.0.1/32 if it's not already in there.

Assuming this is a v6 problem, that should be ::1/128.

 

[fliegerhermi]

I ended up commenting out the empty mynetworks= config.
The postfix default is to accept from all local IPs. I guess that fixed the problem.

I just wanted to make sure, that everything will still work with outgoing mail limits etc.
I excepted Plesk to leave it blank on purpose.

Thx for the help!