Quoting Tom Patterson (pattersontom(_at_)earthlink(_dot_)net):
I have been experiencing delivery problems with a mailing list digest for
those on the list using AOL. Below is the information which I received
concerning the problem. Has anyone else found a solution to the difficulty?
Use SPF on your outgoing mail server, and sign up to be whitelisted at AOL.
This will include setting up a 'feedback loop' so that complaints from AOL
members can be routed to you for removal.
I have done this and have experienced no difficulties in delivering mail to
AOL since.
All details here: http://postmaster.aol.com/
dave