[Jayce]

I've heard bits and pieces about other open source exchange replacement options out there, but I've never looked into them too extensively. Well, our Exchange server has been down for days and multiple tech engineers are looking into it around the clock and it seems to be that the problem is exponentially bigger than anyone anticipated.

As a result, I can't help but to wonder why bother. At this point (if it were me calling the shots) I'd be considering another option while you're going to have to build from ground up.

Has anybody used any open source exchange solution? I've heard a lot about Zimbra, but as I said I've never messed with anything else.

Just wanted some constructive thought on this field. Thanks!

[CntdwnToExtn]

i haven't used in production but have tested Open Xchange.
We steered clear of it though mostly due to the migration costs from MS Exchange + didn't seem to be all that cost competitive for the 'full' version.
Full version required server edition of either Fedora or Suse.
Express Edition was a breeze to setup (installed over a cut down version of Ubuntu) but database was very small.

Outlook users needed to installed "Oxtender" plugin to access the server - web based was pretty decent.
At the time as well (can't remember specifically, i'd have to dig up my notes) there were problems with the calender and tasks - can only assume they've been fixed though.