CAN SPAM compliance.
Over on the ET blog, Al posted about how CAN SPAM compliance is not sufficient for you to not be spamming.
It’s a bit different perspective, but very complimentary to my post yesterday about what is and is not spam. He and I have both heard from ISP people about how many requests for whitelisting or unblocking are prefaced with, “We comply with CAN SPAM” and how meaningless that statement really is. Al has a longer discussion of why.