According to the tech support rep at ATT internet services (800-833-2120). The current email address to send reverse DNS requests to is: email@example.com
AT&T/SBC Internet Services (DNS Admin)
You need to have most of the following information to have the changes made:
1. Domain Name
2. Email Address
3. Customer Contact Name
4. Service Type (ie Office 768/1500)
5. Company Name (If applicable)
6. Primary Domain (ie yourdomain.com)
7. IP Block + CIDR (ie 10.10.1.1/29)
What you want done, ARIN record change or delegation etc.
You must have a package with at least 1 static IP.
You can also visit http://attis-dns.sbcglobal.net/ to request a reverse DNS setup.