Spammers use some kind of software named "spiders" that crawl the Internet in search for email addresses. So if a link to your email is published on any Web site or Blog... some spider might find it and start firing your mailbox with not desirable email messages.
There a few ways to solve the problem. One very practical way is to encrypt the email address. It is very simple! and you can find it by visiting http://www.mways.co.uk/prog/hidemail.php