Install webmin on your server it is an very easy way to setup and configure mail and is free. Visit their website here >> http://webmin.com/
We always install this on our manged dedicated clients server so they can have some GUI interface and manage their boxes somewhat on their own if they want as well. Also usermin is also a good tool it is also on the webmin website.
Hope this helps!
Jason T. Dickman - Senior Server Tech
Cloud Based Solutions, VPS, Linux, Windows, Dedicated