Zimbra relay local email

Question

I have two mail servers that share the same domain name how do I make zimbra relay email who isn't in the zimbra directory to the other email server

Answer 1

What you are describing is a split domain situation. This is well documented on the Zimbra wiki. What you want is the following:

• By default all e-mail to example.org is routed to Zimbra.
• If the recipient for example.org, for example foo@example.org does not exist in Zimbra, it must be routed to the other mail system.
• If it exists on the other mail system, fine. If it does not exist, then inform the sender.

Basically the commands you need in your Zimbra are the following:

$ zmprov md example.org zimbraMailCatchAllAddress @example.org $ zmprov md example.org zimbraMailCatchAllForwardingAddress @example.org $ zmprov md example.org zimbraMailTransport smtp:the-other-mail-server.example.org

Answer 2

To move mail from one server to the other you will need to set up a per email transport in your transport table. Assuming that the transport table is set up in this manner: transport_maps = /etc/postfix/transport , you would add in a line for each email user@domain.tld transport:[nexthop]

So you would probably use something like

user1@example.com smtp:[192.168.1.2]

This will send user1's email via smtp to 192.168.1.2 (or a domain) without looking up the MX server, which may point back to your original server.

You would then run postmap /etc/postfix/transport which will generate the DB file, and reload postfix.

Answer 3

Server recieving mail for ALL addresses that doesn't even exist, - is fast becoming spam target. So, better to check address existance before accepting mail.

If the second mail server is also Zimbra, you could use the built-in Zimbra capability to spread of users across the mail servers in the same domain - "Zimbra Multi-Server Installation".