Zimbra MTA settings

Question

Hi have some questions for Zimbra v8.0.6GA. Under Configure -> MTA -> Network, I'm seeing a few settings and am not very clear what to do with them.

Web mail MTA Host name
Is this for delivering local mail only (ie not for external mails)? According to this link, it says the following. That's a mouthful but what is "composed messages"? Is this for a multi server deployment where the Postfix server for Zimbra isn't installed on the same box that as the rest of the servers?

Webmail MTA is used by the Zimbra server for composed messages and must be the location of the Postfix server in the Zimbra MTA.

Relay MTA for external delivery
My understanding after reading the doc is that if my ISP doesn't force me to relay outgoing mails through them, and I have enabled DNS lookup, I can leave this blank?

Inbound SMTP host name
Sorry I know this is explained as "If your MX records point to a spam-relay or any other external non-Zimbra server, enter the name of that server in the Inbound SMTP host name field." but I'm not following. Can someone provide an example?

MTA Trusted Networks
The admin doc says "To set up MTA trusted networks on a per server basis, make sure that MTA trusted networks have been set up as global settings and then go the Configure > Servers > MTA page and in the MTA Trusted Networks field enter the trusted network addresses for the server." However I see out of the box it has default networks setup for the server whereas on a global level it's blank. Does this mean there is a bug with the install software and I have to copy the setting from the server to the global setting?

Solution

Webmail MTA hostname

Exactly what it says. It's hostname for your server. Since zimbra can be clustered, and you can have multiple servers each one should (ideally) have unique hostname. eg: mta1.myzimbra.tld mta2.myzimbra.tld

This setting should match your unix hostname (for RHEL located @ /etc/sysconfig/network)

Relay MTA for external delivery

Usage scenario: Your zimbra is on your LAN behind a NAT. You use it primarily to send mail in your organisation/company, but your network admin allows connections only to ONE specific external SMTP server. Your e-mail is [email protected] and you want to send an e-mail to [email protected], you need to specify external MTA relay hostname. So it goes: your internal zimbra->external MTA->gmail

Inbound SMTP host name

You do not trust zimbra amavis to sort out your e-mails and do spam and virus checks. Your MX points to some other machine that does all that for you and then push it to zimbra. You need to set that hostname so zimbra knows where your e-mail comes from.

MTA Trusted Networks

On a zimbra cluster (multiple servers, one for ldap, other for mta, third for store, fourth for proxy) you should not use global settings for trusted networks. Trusted networks can, depending on your configuration, relay without auth and do some other stuff that non-trusted IP's cannot. If your using monolithic zimbra conf (everything on one server) you can use either global, or specific settings.

I hope that clears all the issues for you. If you have more questions, ask :)