On Tue, Sep 16, 2003 at 05:53:39AM +0100, Dave Airlie wrote:
> you don't need an MX record.. an A is tried if no MX exists..

True -- i didn't realise this.  For those interested, seems to be a
requirement of RFC974.  I wonder what prompted the author to give the
'benefit of the doubt' to servers with no MX records?  Historical
reasons?

RFC 974                                                     January 1986
Mail Routing and the Domain System

   The explanation of how mailers should decide how to route a message
   is discussed in terms of the problem of a mailer on a host with
   domain name LOCAL trying to deliver a message addressed to the domain
   name REMOTE.
   [--snip--]
   It is possible that the list of MXs in the response to the query will
   be empty.  This is a special case.  If the list is empty, mailers
   should treat it as if it contained one RR, an MX RR with a preference
   value of 0, and a host name of REMOTE.  (I.e., REMOTE is its only
   MX).  In addition, the mailer should do no further processing on the
   list, but should attempt to deliver the message to REMOTE.  The idea
   here is that if a domain fails to advertise any information about a
   particular name we will give it the benefit of the doubt and attempt
   delivery.

-i
-- 
SLUG - Sydney Linux User's Group - http://slug.org.au/
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