Question Solve Problem with local delivery/domains, but still allow sending mails through Plesk

[s5n]

Hi there,

I have the following scenario. I have a Plesk server (Plesk Obsidian Version 18.0.28 - CentOS Linux 8.2.2004 / postfix / courier) with some Domains on it. Some of them use their own Exchange with their own MX entry to receive the emails directly. The respective exchange servers of the domains send their emails via the Plesk server (as a smart host, so to speak). To do this, an email account is set up for the respective domain.

The problem

The problem is - and it is probably already known as I read in the Plesk forum (only a solution I have not yet found) - that when an email is sent from Domain1 to Domain2 (both on the Plesk Server), the mail is delivered locally. Since Postfix thinks that the domain is also local and does not consider the different/external MX entry. This of course means that Domain1 cannot send emails to Domain2 that are not set up on the Plesk server respective Domain2. The sending of the email is therefore rejected and not repeated with the external MX entry. Since the respective domains only use one mail account for sending, the sending of the emails then naturally fails for virtually all possible emails from Domain2.

So, how can I solve this (or what do I have to set up in Plesk) that I can send E-Mails from Domain1 (external Exchange, sent via the Plesk server) to a domain that is also on the Plesk server but has also has an extern MX Entry. Like this:

Domain1 -> Plesk server(hosted Domain) -> external MX -> external Exchange for Domain2

Many thanks for your help.

Best regards

e.g. at [1] suggests to disable the mail service for the domain. But the other goal is that the hosted domains could send their E-Mails with their Exchange through the Plesk Server, which is then no longer possible.
So, the next question would then be, if I had to disable the mail service on the Domain, how could I give the Domain the possibility to send mails from their external Exchange through their own "Hosting/the Plesk Server"?


[1]  Mail to external mail service is delivered locally on Plesk server

 

[Kaspar]

You have your Exchange servers configured to send email trough a Plesk server? That doesn't sound right or perhaps I am missing something (which could be quite possible). What the benefit for this setup?

 

[s5n]

The benefit is, that the IP from the PleskServer (Mail,Web) has a good reputation and everybody could send emails from it. The IPs from the ExchangeServers are sometimes dynamic with all the disadvantages. Have you ever tried to send an email from a dynamic IP to eg. google? Good luck with that ;-) But I'm always open to new suggestions.