Open Source "Messaging" server

[Mike Lovell]

I am in a position where I might be building a new mail server for an 
acquaintance of mine. I talked with the person and it was decided that 
web based mail would be nice but support for a stand-alone client app is 
necessary. Not big deal with just mail. Setup Postfix and Dovecot. Done. 
One additional feature that would be very nice is to have calendaring 
support with the ability to do shared calendars among user accounts. At 
first I was thinking using Lightning with Thunderbird. But then it 
brings up the question of how to do shared calendars and what calendar 
server to use. I thought about just setting up Zimbra to keep everything 
together but it is being a little pain to set up. So I am bringing the 
question to the list. What would you all recommend for setting up a 
"messaging" server that supports email and calendaring?  My only 
requirements are stand-alone client support, good spam filtering, and 
calendaring. Things like web mail, web calendar, and LDAP or AD 
integration would be nice as well. Thanks for any response.

Mike Lovell

P.s. Can we keep the OT flame wars to the minimum on this thread? :)

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