Perhaps this will alleviate some confusion. * All this draft does is define an MX that says "you can't send mail here." It's intended for domains that handle no mail at all, but get mail anyway due to typos or brain-os. There's no hidden agenda. Really. * It has been widely implemented in Exim, Postfix and other MTAs for nearly a decade. If there were severe damage, we'd probably have noticed by now. The fact that it's widely implemented suggests that people find it useful. * The part in the draft about sending and receiving was confusing and unhelpful, so I rewrote it. Now it says you SHOULD NOT send mail from a domain that publishes null MX. This is both on principle, don't send mail if you don't want an answer, and practice, since many, many MTAs reject mail from domains without a resolvable mail server. (Remember, SHOULD NOT means don't do this if you want to interoperate.) R's, John