On 9/3/07, John S Russell
I'm not sure why you're bringing this up. Everyone else is talking about basic low-level connectivity - they ability for a mail server on network (C) of the diagram to deliver mail to and MAX on (B) if (A) is unreachable, or vice versa.
You're the only one who's brought up higher-level aspects of mail
Makes me feel special ;-)
processing and handling at this point. We're all talking about getting mail delivered to a valid MX, and you're the only one talking about what happens if the MX config is screwed up.
Sure, if Joe has his MX on network (A) configured correctly, and his MX on network (B) configured to do Stupid Shit, then (B) will surely do Stupid Shit. I don't see why you'd think this would be so.
Ok, this is the last post, I promise. I completely agree. If the MTA in [B] is configured to do Stupid Shit, it will do it - no argument about this. My main point was that I've seen that Stupid Shit being done in 99% of cases, while only 1% had MTAs properly configured (and I'm sure that Joe's server is properly configured, at least it is now ;-). If you take a look at some big e-mail providers you will see that they don't bother with low priority MX records - check hotmail.com, check yahoo.com (they don't even do it for their own domain). Google does this and I bet they have some *very* smart logic behind it. I'll go back sorting out my own e-mail now ;-) Bojan