Here is what I would suggest you try:

1. Start reading news.admin.net-abuse.email on Usenet. You can read and post from google via: http://groups.google.com/groups?hl=e...et-abuse.email
You can get alot of information and help from the regulars on NANAE. Remeber, this is Usenet, not everyone is nice and you can get flamed pretty bad if you don't follow the posting rules.

2. Check sites like spamcop, spews etc....They have lots of info about setting up block lists in mail servers.

3. If you are in some blocklists, find out which ones by checking the lists yourself. You will find links to thoses on www.spews.org etc....
Most of the block lists that deal with open mail relays have an option for testing the relay. You can check your progress yourself by testing you own server via these sites. Once you are no longer open and have run the test, most of the time you will get removed from the block list. You can also contact the admin of the blocklist / test site and see if they can speed up the process for you.

4. Once you have closed your open realy and have tested it, then post on NANAE. This way, you minimize the possible flamming that could occur. If you are honest and open with the users on NANAE, they will be a great resource for you.

5. There is also a NANAE type group called sightings. (Check google). This is a place were users / admins have posted the spam that they have recieved. There is a process that must be followed for it to be accepted in sightings but the FAQ explains it all. This groups becomes a record for others to be able to check host domains and ISP's to see if they are spam friendly.

Hope this helps. I have been down this road before..Good luck.