Anyone know of a freeware (or cheapware) email server that has a web client?

[PingSpike]

I've been looking for a freeware mail server that offers a web interface for some users we have on the go. Price is a factor since we're a nonprofit.

 

[catrats]

Check out DeskNow Mail and Collaboration server which they offer in three different versions. If you like the lite version and would like to upgrade to the professional version, they offer discounts to non-profit organizations.