AOL is looking for input from ISPs and ESPs to better understand how you handle data sent to you by AOL.
In regards to bounces – users unknown, specifically – could you please explain the following:
When do you take action on clients because of bounces? What is your threshold for acceptable, and not? Do you have an escalating level of punishment for people who break your thresholds?
What is your threshold for “acceptable” in regards to inbound mail streams and “users unknown”? What do you do when that threshold is breached?
You can send answers to me directly (laura-blog (at) wordtothewise.com) and I will forward them to the folks at AOL. You can also post them in the comments and I will make sure the AOL folks see the answers.