[unisog] DNS Hostname and SMTP Helo

Bill Martin BMARTIN at luc.edu
Tue Jan 30 19:58:13 GMT 2007


Some time back, we had saw an influx of mail originating at hosts
providing a "helo" (hostname), where (hostname) usually started with
some numerical value.

Either I've lost my mind or there use to be an RFC that qualified
"acceptable" host names and if I recall, this ties in with DNS, in that
a hostname (especially in this case) should never start with a number,
only a letter.  

Is this still an acceptable method to reject?  That is, if a host
announces itself as ([0-9]{x}hostname)??

Any help would be greatly appreciated
-bill-




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