Open source MS Exchange-equivalent for Linux/Evolution...

Hi!

I'm trying to find a free and open source equivalent or alternative to
MS Exchange. All clients are running the latest version of Novell
Evolution. I need the ability to manage e-mail, calendars, tasks, and
contacts.

The ability to schedule group meetings would be a bonus.

I've been looking at opengroupware, but it doesn't seem to support the
latest version of Evolution as a client - and this is a must for me.

Thanks in advance!
Cyp.

I have read favorable comments about Open XChange
http://www.open-xchange.org/, though I have not used it personally.

In my own experience I found that the Web CMS approach is much more
usefull, versatile, powerfull and easy to extend than the "Exchange"
approach for group collaboration.
I use Plone that basically is an Object Database with a rock solid
security system (based on roles) and a framework to plug different
types of contents (documents, files, calendars, ...), integrated and
asthonising Text Search Enginne and workflows for the content states.
It's extremnly easy to setup, even for the Cluster configuration
(ObjectDatabase Server<-> Redundant Web/App Servers). Windows and Mac
versions are a matter of Click "next" and even newer versions of Ubuntu
(and maybe another Linux distro) have it ready to run.
https://launchpad.net is a good example about what's possible with
Plone and IMpossible with an "Exchange" server.

http://plone.org/products list available plugins (products in the
Plone terminology) you can not even dream about when using the "OLD"
Exchange approach to group collaboration.

Customizing Plone is also really easy since you have an integrated
template system that play nice with Macromedia and other Web tools and
scripting support through python (scripting an Excel spreadsheets with
VisualBasic is a hacker's work when compared to the easy and beauty of
Plone python scripts).