Michael, I'm not so sure that its altogether that far off topic. I've heard all kinds of interesting strategies for bringing XML to HTTP, from WebDAV on down, but it would seem to me that work on a similar protocol for upgrading SMTP to an XML basis could provide some powerful dividends. Among other things, it would make it easier to provide consistent mechanisms for handling mailing lists, including unsubscribe information, and it could even make it reasonable to handle such XMail through HTTP ports as readily as through SMTP ones. Just an addled thought. Good luck on getting some standardization on mailing lists, though.
Some people are just plain clueless.
I know I'm going to get about 5-10 such replies in response to this post. Sorry about the off-topic post. I'll say no more about it. Do the planet a favor.