SUMMARY: Mail and Calendar servers

 Thanks to all who replied.

Dirk-Willem van Gulik
Jeff Kennedy
Neil Hunt
Jed Dobson
Craig Reynolds
Ric Anderson
Matthew Boeckman
Ryan (mattyml at daemons.net)
eshafto at mac.com
Rich Kulawiec
Heilke, Rainer
Chris Hoogendyk
Mast, Art
Yura Pismerov

Seems a number of people are using iPlanet mail and calendar servers, with
varying degrees of satisfaction.
Most noted that outlook can use IMAP. The main problem is the 'Groupware'
stuff. Email has many solutions
but there is very little that competes Exchange and the ilk.

Also got a warning about using outlook. Unfortunately many here people seem to
like the interface.

Other options people came up with:

Lotus Notes and Domino which run on various platforms.
GroupWise
Corporate Time http://www.steltor.com
Meeting Maker from On Technology
OCSweb http://www.obsidian.co.za
CyBozu  http://www.cybozu.com/
Communigate Pro http://www.stalker.com/
IMP and HORDE http://www.horde.org/
SIMS

 Original Question:

  Hi,
    The powers that be want to replace our current mail system and we really
don't want to use Exchange. Has any one used the iplanet suite of
mail/calendar etc services? Most of the desktops will be NT/Win2K so it will
(unfortunately) need to be compatible with Outlook.

  Functionality needed is:

     Mail
     Shared Calendars
     Room/Resource bookings

   Any suggestions, war stories would be greatfully received.