AOL

We are on the Feedback loop with all of our sending servers and these are also on the whitelist.

The AOL Whitelist is a list of IP addresses which we register with AOL to say
"we are a responsible email marketing company, many different people are sending double opt-in best practice emails from our servers, please do not immediately black list our servers if you members mark any of them as spam, please let us know and will sort it out so our other customers don't suffer."

You can only achieve the AOL Whitelist by joining the AOL Feedback Loop (FBL) amd maintaining a good reputation.
This causes every email from our registered servers, that are marked as spam to be automatically forwarded to us.
Using our email tracking capabilities we can find out who marked the email, who sent the email and when.
This enables us to manually unsubscribe the complainer.
AOL states that marking an email as spam is as good as an unsubscribe.
Especially as once someone has marked email as spam any email from that sender will go into their spam folder and negatively effect our reputation.

http://postmaster.info.aol.com/