Umm, I'd be checking into your credit, to make sure you're not an identity-theft victim.
Hopefully all this is just an email issue, in which case you can just delete them. If it's broader though, you'll have to take action, ASAP.
You should be able to get a free yearly credit check, many banks/CU's offer them, or can point you to someone who does.
Once you get that ironed out, I'm sure AT&T customer-service can remove your email from this account, and you won't get someone else's bills, going foward.