RE: virus mail ignores MX?

["Keith T. Morgan" <keith.morgan () terradon com>]

More than 70% of our spam that is blocked is blocked at the secondary
MX.  I agree and fully believe that spammers seem to be targeting
secondary MX's directly, and most likely for the reasons listed below.
We've seen instances where the same spam message is delivered to both
mail exchangers.  This is likely spammers hoping that one has less
anti-spam filtering than the other.

> Hence even if the RFC had specified a MUST, a virus writer 
> could make an intelligent guess that a backup MX server is 
> probably not as well protected as the primary server and 
> hence better his/her chances by violating the RFC, and using 
> the backup server. Any protection against such an attack 
> would involve too much state tracking and is probably not 
> worth the effort. Its much better to protect all servers equally.
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