Welcome to the forums,
You might want to specify, as I assume you mean
Message Processing Platform (
for postfix) heck some pages actually mention it with an interesting spelling
1 2 - but you could always be referring to the very cool
MySQL Pool Poller 
I actually used to work with the guy who developed that - more on it:
http://dev.mysql.com/tech-resources/...egy-part1.html http://dev.mysql.com/tech-resources/...egy-part2.html
-I know, shameful plug because the name matches, you really would be hard pressed to find a reason to use that with zimbra.
(or other things that come up when you
search MPP)