The last two days, I've received emails through two addresses registered over the years with The Guardian. These were addresses used to register for competitions, forums etc. I never gave permission to be spammed with "GuardianUnlimited Today". That's rather sad as they used to be The Good Guys.
Fortunately, the addresses they were spamming are (or were, as you'll see) Sneakemail addresses. Sneakemail allows you to createdisposable email addresses for just these kinds of things. When they start spamming you, you know the source and how conned you into supplying the email address. What's more, once it starts getting spammed you can delete it. Lovely!