I figured this out quite a few years ago. The first time they spammed me, I signed in and turned off anything that said they would send me email. The next time they spammed I deleted my account and black-holed the email address I used to sign up with them. I gather things continued to go downhill from there (e.g. spamming all your contacts).

I can't understand why people would continue to use a web site from such an obviously dishonest company.