So say you have a customer ... you can set up a page like this and you and he can keep a flow of communication and information on it ... you can make it private or public. Or you can have a messenger like there is on this site for service and inquires.
Of course it would be good to get your emails more regularly than I have ... sorry.
This is a link to infrmation as well as a good video to explain what is drual and a content mamagment system ...
http://www.metroecho.com/info