Perhaps I'm missing it, but what does changing the delivery protocol buy you? XMPP does little to nothing more than email in terms of sender verification. SPAM would continue unabated.
> XMPP does little to nothing more than email in terms of sender verification.
SMTP doesn't do any verification at all, does it? XMPP uses SSL if possible and otherwise does a dialback so you can at least be sure the message was sent from the server it claims to be from.
The other aspect is that XMPP is young enough that it can still change to do more (since there are only a handful of clients and servers, as compared to SMTP). As far as I can tell, SMTP is completely stagnant and any improvements that can't be made unilaterally won't happen. (I'm not very familiar with SMTP, I'd love to be proven wrong.)
No, not even close. SPF is not a spam prevention measure. It's just a way of protecting innocent senders from being impersonated by spammers. DKIM does a better job at the same purpose.
