I have recently switched to using forms to combat spam on some of my sites. The form simply sends the email, but keeps the email address hidden. The form contains the same fields as an email. There is a dropdown list for the subject. Depending on the subject, the mail is routed to the best person to help them.
Here is the text I use to explain the form:
Why do I have to fill out this form? You can be assured that your email will be sent to us immediately upon hitting the 'send' button. Due to an ever increasing problem with spam, we have decided to refrain from publishing our email address on the public internet. This helps to insure that we are receiving a higher percentage of legitimate emails. The result - we spend more time answering your questions and less time sifting through spam. In addition, when you select 'My message concerns' from the drop down menu, your email is routed to the person who can best help you.
So far I see no decline in the number of legitimate emails.