Pierre,
I run my own mail server on a T3 line, whereas Shaw Cable owns the line.
I not only ran my mail IP through OAL's verification system but also myriads of other databases, such as CBL, NJABL, etc.
My IP is not blacklisted anywhere as far as I can tell and my server does not allow mail relay, something that would get you on the list.
I am familiar with ISP's blacklists and seem to get on the "Earthlink" one 2-3x a year. However, the rejection is always immediate.
With AOL, the "undeliverable" message takes many hours. Also, if it were a spam issue, I don't think it would try 20 times over hours but simply reject the message immediately.
I will try some tests using a proxy server in Europe and see what happens.
Bernie