Best Replacement for Exchange for 35-user office
 

Hello,
I am wondering which email app would be the best, easiest to use replacement for Exchange? This office has about 35 users, with the largest email account being about 4GB. There are four others around the same size but most others are much smaller and maint. and overhead are concerns. Calendaring is not heavily used but would need it to be in the future.
The replacement needs to be fairly straight-forward and easy to get going if possible.
Thanks very much.

http://www.egroupware.org/

you can go with web-based client, or MS Outlook, or any other mail/calendar client in conjunction with egroupware.

Also look at Zimbra Open Source.. http://www.zimbra.com/

view the hosted demo.. http://www.zimbra.com/products/hosted_demo.php

pretty slick, and the ajax web client is very nicely done. Or you can use any standard mail client.

I found install to be straight forward, after reading the docs i was able to get Zimbra installed and running in under an hour.

OpeneXchange?