Exchange server replacement

[Jeff]

Hi All,

Does anyone have any suggestions on an MS exchange compatible daemon for 
RH? I don't need any of the fancy admin stuff - all I need is the abilty 
to fool MS outlook into thinking its connecting to an exchange server to 
collect mail.

Ive done a quick google search but havent found what ive been looking for.

Another requirement - I needs to be free ;p

Thanks
Jeff