There may be an issue with sending e-mail to AOL by SACWIS.  AOL is enforcing tight security on e-mail sent to them or their customers.  Organizations that are having issues should probably look at these items:

1.  Open Relay on mail server
2.  No Reverse DNS
3.  Virus/Worm that is sending SPAM
4.  Hijacked mail server

For the first two issues, you can go to http://www.dnsreport.com/ and run a test for these two issues (It will warn you about a host of other potential issue as well).  For the last two issues, you would have to have an up to date anti-virus software and anti-SPAM software.  If you find that your system(s) have been hijacked, you will probably need a security professional to assist you with clean-up.

If you are having further issues with sending to AOL, please contact AOL's business tech support department @ 888/212-5537 and ask for Christy.

One thing to note:
Myth: If you have a reverse DNS entry listed in your DNS server, you have reverse DNS properly set up.
Fact: This is often not the case. You need TWO things in order to have your DNS set up properly:

• 1. Your DNS servers (or your ISP's) MUST have the reverse DNS entries set up ("25.2.0.192.in-addr.arpa. PTR host.example.com").

2. AND your ISP or bandwidth provider MUST set up the reverse DNS on their end, so that DNS resolvers around the world will know that your DNS servers are the ones to go to when looking up the reverse DNS for your IP addresses.