I went about it a little differently. I placed a simple email form, just email address and comment, at the bottom of just about every page. I tell the customer to let us know if they're having difficulty finding what they are looking for or if they have any questions. I even made their email address an optional field, so it really was a way to just let us know what's going on.
My goal was to make it as easy as possible for people to contact us via email, so they wouldn't feel compelled to call. I don't even tell them that they're sending an email. I just tell them to let us know what's on their mind by filling in the form.
Our email volume went way up, and phone calls went down. 99% of people fill in their email address. Some don't have a clue what their email address really is, and we are never able to reply. That's rare though.
Before this, we had a simple email address with a mailto link.