The one that pisses me off is the one that said DCC identified the message as confirmed spam.

No, the DCC docs explicitly and carefully say that they identify bulk messages -- which a newsletter obviously is -- and that only the recipient can determine if it's unwanted, making it spam.

If ISPs start flagging all bulk as spam, newsletters are in trouble. I can't imagine that will last long on a widespread basis, but could really suck for the people stuck on smaller ISPs who do it.