Thank you for contacting the AT&T Postmaster.
The mail-server IP address(es) associated with your request will be removed from the block list within 24-48 hours from the date of this letter. AT&T and its affiliates do NOT intentionally block legitimate mail in the course of our anti-spam initiatives and regret any inconvenience this may have caused. If the IP that was recently blocked begins to exhibit the characteristics of a compromised network object or is compromised by an offender of Acceptable Use Policies, the IP address will be blocked again.
ADMINISTRATORS: Please thoroughly check your IP logs before requesting removal. You must determine that all traffic from the blocked IP is actually from your mail servers to ensure your network is not compromised. Administrators who fail to do this may experience subsequent and more resolute blocking.
Thank you for helping AT&T Internet Services network combat spam in all its forms.
Regards,

AT&T Postmaster
Chief Security Organization
abuse_rbl@abuse-att.net
https://www.att.com/postmaster/