Many websites are the subject of spider attacks, bots automatically collect your emails off your contact
page. The software used is typically called "Email Harvestors", lists of emails are harvested and spam
email is sent out to the list.
You need to discuise your email, you can do this by putting it on a picture or getting some code off a website.
Or with Xsitepro you can do the following.
To add your cloaked email, right click on your chosen webpage, click widget wizard > Misc > Email