Enable Milter server
from web admin console:Configure - Global Settings - MTA
check Enable milter server
by command:
[root@mail ~]$ su - zimbra
[zimbra@mail ~]$ zmprov ms `zmhostname` zimbraMilterServerEnabled TRUE
[zimbra@mail ~]$ zmmailboxdctl restart
Stopping mailboxd...done.
Starting mailboxd...done.
[zimbra@mail ~]$ zmmtactl restart
Rewriting configuration files...done.
postfix/postfix-script: refreshing the Postfix mail system
Stopping saslauthd...done.
Starting saslauthd...done.
Stopping opendkim... done.
Started opendkim: pid 12355
[zimbra@mail ~]$ zmmilterctl start
Starting milter server...done.
[zimbra@mail ~]$ zmmilterctl status
Milter server is running.
Specific senders for a distribution list
zmprov grr dl distributionlist@yourdomain.dom usr user@yourdomain.dom SendToDistList
Allow specific domain to send to a distribution list
zmprov grr dl distributionlist@yourdomain.dom dom thedomain.dom SendToDistList
Deny specific domain to send to a distribution list
zmprov grr dl distributionlist@yourdomain.dom dom thedomain.dom -SendToDistList