Hi, We set up CommuniGate Pro on SME5.5 early this year to test for a client who needed email w/List Serv - installation was pretty simple, just follow the instructions on their website for redhat linux, nothing tough. Be warned though, configuration can be a real bear!! Advise keeping it simple and take defaults wherever possible - it's easy to get lost & break something if you like to tweak things. Other than that, it's a great program, low CPU overhead, very robust, MS Outlook works great with it - big network stuff - overkill for most smb's.