When I was restart service its display warning issue in zimbra server, might be this can be the issue ??
Starting ldap...Done.
WARNING: Disk space below threshold for /opt/zimbra.
Starting zmconfigd...Done.
WARNING: Disk space below threshold for /opt/zimbra/logger/db.
Starting logger...Done.
WARNING: Disk space below threshold for /opt/zimbra/store.
WARNING: Disk space below threshold for /opt/zimbra/db.
WARNING: Disk space below threshold for /opt/zimbra/index.
WARNING: Disk space below threshold for /opt/zimbra/redolog.
Starting mailbox...Done.
Starting antispam...Done.
Starting antivirus...Done.
Starting snmp...Done.
WARNING: Disk space below threshold for /opt/zimbra/data/postfix/spool.
Starting mta...Done.
Starting stats...Done.