Q:

Alternatives to Exchange: OpenXchange vs Zimbra vs others?

Looking for recommendations on alternatives to using MS Exchange server. 
Email, calendering, ease of administration, archiving being the priority. Nice to have features being mobile support and internal IM.

A:

I'm happily using Zimbra:

ease to administer
simple to the users
very well integrated
internal IM
resource/calendar/contacts/document sharing
very well synced with OS clients (iCal, Thunderbird, iSync, iPhone)
easy and fast used with iphone

The only thing is the upgrade procedure, to be quite manually handled if you had made some strong graphic customizations ... but it is really simple.
I'm recommending ZCS .

