[eli]

I actually have run a mail server before, and now I gladly pay someone else to do it for me :)

Point taken, but I've been on the receiving end of what I would consider false-positive blocks by Spamhaus & co. They sometimes have policies about what's considered spam that I don't think all their end users would agree with. I've been blocked for having an IP address on the same provider as someone else who allegedly advertised their website via spam. If you're running a mailing list, dealing with the anti-spam stuff is at least as big a problem as the spam it was supposed to solve.