our Zimbra server has been running for almost 2 years without major issue.

Two days ago, we were unable to send outgoing mail.

/var/log/zimbra.log gives:

Oct 14 11:22:17 mailserver postfix/smtp[15130]: E98B0DA8153: to=<xxxx@gmail.com>, relay=41.204.XX.YY[41.204.XX.YY]:25, delay=0.16, delays=0.01/0.01/0.13/0, dsn=4.4.2, status=deferred (lost connection with 41.204.XX.YY[41.204.XX.YY] while performing the EHLO handshake)

I'm using my isp smtp server for outgoing mail: 41.204.XX.YY 25 which used to work perfectly.

My Zimbra server settup is:
Web mail MTA Hostname : mailserver.xxx.com
Relay MTA for external delivery : 41.204.XX.YY 25
DNS lookups ticked

Does anyone ever experienced this EHLO handshake issue ?


Zimbra : Release 5.0.8_GA_2462.RHEL4_20080709163257 RHEL4 FOSS edition