Incoming Mail Problems

Troubleshooting incoming mail

If you're having trouble receiving mail from outside, you need to find out where the message is failing.

When sending your test message, check the Log Files, especially /var/log/zimbra.log, on your MTA server.

It's often helpful to tail the logfile as you send the message:

 tail -f /var/log/zimbra.log

If you see nothing logged (no connection, nothing) then the problem likely either DNS or your Firewall.

Firewall

To troubleshoot your firewall, it helps to have an account on a system outside of your network.

For mail to flow inbound, servers on the internet need to connect to your MTA on port 25.

DNS issues

The mail domain that your user accounts are created under must have an MX record. To test this:

 host -t mx domain

The IP address returned should be the IP (public or private) of your MTA. If it's the public address, make sure that the Firewall is forwarding port 25 to the MTA.

Mail is delivered to the MTA, but not to the mailbox

If there is a line in the /var/log/zimbra.log like:

 postfix/lmtp ... deferred ... connection refused

There is no connection to port 7025 to perform LMTP delivery.

The host that the LMTP delivery is made to will be the value of the account's zimbraMailHost attribute.

To test this, telnet from the MTA to the zimbraMailHost on port 7025 by name (not by IP). If this is resolving to an IP address on your Firewall, make sure the port is forwarded on to the zimbraMailHost.