At the same time, I think it is a good idea to have a non-domain email address related to your business. For instance, I have NowAssistingYou at a popular online email address that I use when I sign up for things like Yahoo Groups and forums. That way the loads of emails aren't taking away bandwidth from my site and it lowers the chances of spam to my regular website address. By the way, I use a small script on my site to prevent email harvesters from getting my address - so far it's working. ;-)
Since we're on the subject of email addresses, there are some you should avoid completely even though they might seem like obvious choices like: firstname.lastname@example.org
etc etc - spammers that have only harvested your domain name will use these common prefixes to spam you.