[Mimedefang] sending relay has no MX record?

Kevin A. McGrail kmcgrail at pccc.com
Sat Jan 29 19:35:36 EST 2005

I believe an MX was designed as a Mail Gateway record for machines not 
directly connected to the network.  Therefore, since an A record is for 
machines that are connected to the network, an A record should be enough to 
allow for mail to be delivered.

I know in practice that using only an A record works and is frowned upon.  I 
also know that an MX record has been expanded more and more.  But from an 
RFC perspective though, I'm not sure it's "incorrect" to just use an A 
record without an MX record.  Hopefully someone else can comment but in the 
meantime, I'm not sure it's a legitimate test for spaminess.


> Am seeing some spam where the sender's From_ address's domain
> doesn't have an MX record.  Was considering noting that fact
> in the header as an extra X- field, and then letting SA score
> it negatively. Has anyone tried that sort of thing?  Can
> you offer some prototype code that does something like that? 

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