frequently during the day, the MTA services & STATS stop and restart a few seconds later.
Here's an example of the email messages that I receive.

-- STOP message
Feb 20 09:28:02 zimbra zmconfigd[638]: Service status change: zimbra.geatrentinaservizi.com mta changed from running to stopped
Feb 20 09:28:02 zimbra zmconfigd[638]: Service status change: zimbra.geatrentinaservizi.com stats changed from running to stopped
--START message
Feb 20 09:29:03 zimbra zmconfigd[638]: Service status change: zimbra.geatrentinaservizi.com stats changed from stopped to running
Feb 20 09:29:03 zimbra zmconfigd[638]: Service status change: zimbra.geatrentinaservizi.com mta changed from stopped to running

Can you help me understand what's going on?

thanks
Alessio

Ubuntu 10.04 - Zimbra 8.0.2 OSE