DNS question, null MX records

Eric J Esslinger eesslinger at fpu-tn.com
Tue Dec 15 09:17:40 CST 2009

I have a domain that exists solely to cname A records to another domain's websites. There is no MX server for that domain, there is no valid mail sent as from that domain. However when I hooked it up I immediately started getting bounces and spam traffic attemtping to connect to the cnamed A record, which has no inbound mail server (It's actually hitting the firewall in front of it). (The domain name is actually several years old and has been sitting without dns for a while)

I found a reference to a null MX proposal, constructed so:
example.com    IN    MX 0 .

Question: Is this a valid dns construct or did the proposal die? I don't want to cause people problems but at the same time, I don't want any of this crap to even attempt to deliver on this domain to any of my servers.

Eric Esslinger
Information Services Manager - Fayetteville Public Utilities
(931)433-1522 ext 165

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