AOL 421 errors

We've noticed a surge in 421 e-mail errors from AOL. Message soft bounced for '###@aol.com', '4.3.2 - Not accepting messages at this time ('421', [': (DYN:T1) http://postmaster.info.aol.com/errors/421dynt1.html', 'SERVICE NOT AVAILABLE']) []' It seems as though they've tightened down their policies. We're pretty good at preventing spam with our IronPort anti-spam gateways and internal policies. We've also subscribed to their FBL notification service. I'm surprised at the types of messages AOL customers consider as spam. Anything and everything: university admission acceptance notices; instructor class assignments; photos from friends; etc. matthew black california state university, long beach