That’s pretty standard I’m afraid Dom. Any published email address is used for these. I have “spam” apparently going out from all of my domains pretty much.
Not much you can do, although I have developed a small tool that I’m beta testing that will allow you to create “images” of your email address which are much harder to scrape. You can take a look here: http://www.oggs.com/tools/ may be useful (please feel free to feed back).