iPhone Users: Check Your AT&T “Marketing Settings”
It would seem that when you open up a new account with AT&T they go ahead and sign you up to receive spam marketing material via email, text message, your phone, and by paper mail.

Ummmm, yeah, I’m going to have to uncheck these.
If you need to do the same, go to att.com/mywireless. It’s at the bottom of the Account Information tab of the My Profile section.

[...] AT&T Marketing Settings – How to adjust your account so you don’t get spam from AT&T. [...]