Server error: 550 5.1.1 with google mail mx services

OS type and version CENTOS 7
Webmin version 2.105
Virtualmin version 7.9.0
Related packages POSTFIX

Hello, good morning, I will try to explain my problem as best as possible.

I have my server on centos7 with webmin and virtualmin php 8.0 + postfix, imap/op3 dovecont in which I am hosting several client domains which work normally.

I have and, on it is configured with normal mail in virtualmin with dkaim and other elements installed, it works well, it sends and receives without problems.

In there is a DNS configuration since the client has his email with Google Works, for which in the DNS configuration a change is made in the mx by lso aspmx from Google

When sending emails from any address on to any address on I get the error message:

Some of the recipients did not receive your message.

   Subject: demo
   Sent on: 01/26/2024 9:29 a.m. m.

The following recipients cannot be reached:

   '' on 01/26/2024 9:29 a.m. m.
         Server error: '550 5.1.1 <>: Recipient address rejected: User unknown in virtual alias table'

From any other mail system, receives emails and sends without problem, but when emails are sent from to, the aforementioned error returns.

emails from have been sent from roundcube and from outlook, they show the same error


  1. in the list of servers in postfix configuration mail aliases option, I have added the mail alias to the list.
  2. I have restarted postfix.
  3. I have carried out sending and receiving tests

I urgently ask for help, please if someone can give me some light on what I should do since I have many communication problems between these 2 domains.


Do you have email enabled for domain2?

If so, the system is trying to deliver locally between domains on same server despite the DNS records.

Turn off email feature for domain2 and it should start working correctly.