AOL Instant Messenger (AIM) is an ad-supported instant messaging application. It is difficult to block AOL Instant Messenger (AIM) using rules due to the wide range of ports it can use and the way AOL can reconfigure itself to use another port if a particular port is blocked. AIM will also change its server ip address from time to time. The best way to block AIM is to utilize SonicWall's Intrusion Prevention Service.
If you would like to use firewall access rules, the following information will be helpful:
AOL's login servers (login.oscar.aol.com and login.icq.com) are on these subnets: 126.96.36.199/16 and 188.8.131.52/16.
AOL's web-based chat server uses toc.oscar.aol.com on a variety of addresses in the 184.108.40.206/16 network.
You may want to create LAN to WAN firewall access rules denying destination addresses on the following subnets: 220.127.116.11 (255.255.0.0) and 18.104.22.168 (255.255.0.0).
NOTE: These rules will also likely block AOL entirely, not just instant messenger.