On Sat, Dec 27, 2008 at 01:33:47PM -0500, Sahil Tandon wrote: > jkinz mentioned the connecting "system"; that is to say, the connecting > client. That client needn't be the MX for the domain from which email > is arriving. Negative, "system" -- that is to say "domain" in this case. Consider yourself surprised.. email systems (domains) that don't have mx's will find themselves having problems despite the fact that its not an rfc requirement.