Relay for unknown domain users

[mrmarkuz (Markus Neuberger)]

This howto explains how to setup a mail relay:

Relaying and Filtering Mail for Legacy Servers with NS8

Let’s see how to overcome an apparent NS8 Mail limitation to filter and relay messages to a backend mail server. This How-To requires some Linux shell knowledge. Why use NS8 as a relay-only SMTP server The NS8 Mail application provides anti-spam and anti-virus features that may not be present in your organisation’s mail server. NS8 Mail can be placed in front of it to improve security with an up-to-date and well-maintained mail filtering system. Brief History In NS7, it w…

In your case it should be enough to just add the relay domain on the main MX.

Create the relay.cf file…

runagent -m mail1 podman exec -ti postfix vi main.cf.d/relay.cf

…with following content:

relay_domains = domain2.com

Reload postfix:

runagent -m mail1 systemctl --user reload postfix

@stefferd

i’ve made sure that it will accept this domain by entering the mail app via runagent and in Python invoke this command:
agent.bind_user_domains([“domain2.com”])

I don’t think this is needed as it lets the mail app use a samba or openldap user domain, see User domains | NS8 dev manual