Using Zimbra for a year now...
I previously used the mail server Mail Enable which is a moderately priced windows email server. To be honest I loved the easy Windows like admin utilities and it was up and running pretty quickly. However it crashed on average once a month, Windows had itís usual stability issues, and trying to combat spam was nasty. I also noticed that for our moderate size (35 accounts or so) we were at times really maxing out the processor. We are a church and really wanted to reuse the older hardware instead of upgradingÖ.so I decided to go down the Linux path (CentOS).
I was evaluating lots of other cheap/free solutions when friends recommend I look at Zimbra. I did and havenít looked back. We are able to reuse our older hardware. I have more active users now with no performance issues, our spam detection rate has skyrocketed, I find it very easy to admin over the web, and Iíve even converted most of our mail client users to use the webmail client since it is so rich.
One hick-up, after running it about 3 months, I messed up a version upgrade (and had a bad backup), but a few posts in the forums and I had other folks bending over backwards to try to help me out. I couldnít believe the amount of community support I was receiving. That has motivated me to try to give back to the community when I can.
Also one thing Zimbra did was make our church more organized & efficient. The web based shared address book and calendar has allowed us to organize and schedule shared resources, manage email/mail campaigns, and let staff & volunteers quick and easy access to church directory information. Also our Senior Pastor is a huge Apple user, so he really appreciated the rich WebMail interface that works well in all of his browsers (as opposed to just our Windows users)..
Thank you Zimbra Team,
Richard G. Vissers