Zimbra reports “ Error: Queue report unavailable – mail system is down ”

During update from one version to another or sometimes when you reboot Zimbra you can get following error:  "Error: Queue report unavailable - mail system is down".

We can find that it does not starts correctly the service postfix MTA. But the system shows that everything is working properly:

zcs @ zimbra: ~ $ zmcontrol status
Host zcs.ilba.cat
        antispam                Running
        antivirus               Running
        convertd                Running
        ldap                    Running
        LOGGER Running
        mailbox                 Running
        mta                     Running
        opendkim                Running
        proxy                   Running
        snmp                    Running
        spell                   Running
        stats                   Running
        zmconfigd               Running

We reviewed logs and services and we see that the MTA is down:

zimbra@zcs:~$ tail -f /var/log/mail.log
Jan 22 11:08:00 zcs postfix/postqueue[19195]: fatal: Queue report unavailable - mail system is down

zimbra @ zcs: ~ $ netstat -nlpt | grep 25
(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)
tcp        0      0 0.0.0.0:7025            0.0.0.0:*               LISTEN      -

We proceed to restart the service postfix hand, indicates that it has raised correctly, but does not work:

Zimbra ZCS @: ~ $ / opt / Zimbra / bin / zmmtactl stop
/postfix-script: fatal: the Postfix mail system is not running
Stopping saslauthd...done.

Zimbra ZCS @: ~ $ / opt / Zimbra / bin / zmmtactl start
Rewriting configuration files...done.
Starting saslauthd...done.

zimbra @ zcs: ~ $ netstat -nlpt | grep 25
(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)
tcp        0      0 0.0.0.0:7025            0.0.0.0:*               LISTEN      -

The problem is that there is master.pid file, which tells the postfix that is raised, but it really is not raised. We looked:

root@zcs:~# locate master.pid
/opt/zimbra/data/postfix/spool/pid/master.pid

And delete it or rename it and then restart the MTA:

zcs root @: ~ # mv /opt/zimbra/data/postfix/spool/pid/master.pid /opt/zimbra/data/postfix/spool/pid/master.pid.ori

root@zcs:~# su - zimbra

Zimbra ZCS @: ~ $ / opt / Zimbra / bin / zmmtactl start
Rewriting configuration files...done.
Starting saslauthd...already running.
/postfix-script: starting the Postfix mail system