Author: J.Darlington (16 Dec 08 12:31pm)
I don't think it would. SPF specifies which IPs are allowed to send mail for your domain; MX specifies which servers receive mail. They're two different animals. In fact, if you're not using your donated domain for actual mail, you should probably specify an SPF record that explicitly states that domain should not be sending any mail at all ("v=spf1 ~all"). That way if a spammer starts trying to spew garbage "from" your domain, receiving hosts that honor SPF can see that you say you're not sending anything and they can safely discard it.