We currently have a Virtualmin Pro (primary) server and a Virtualmin GPL server (rented VPS) and all is working well. The secondary Virtualmin GPL server provides backup services for DNS, MX, LDAP, RADIUS, etc.
What I want to do is easily provide backup MX service, and/or spam filtering for my customers that have their own mail servers and sell this as a monthly or annual service.
I understand this requires a secondary MX record in the customer's DNS...no problem.
I think all it would take is adding a domain to the Postfix relay_domains parameter:
postconf -e 'relay_domains = $mydestination, newdomain.com'
To provide a spam filtering service, I could probably just firewall off the primary MX, except from my mail server (the backup MX + spam filter).
Is there an easy way to do this within Virtualmin or Webmin?
Thank in advance,