convention for MX records

Brad Knowles brad.knowles at
Sat Oct 6 17:20:51 UTC 2001

At 7:05 PM +0000 10/5/01, Bob Zachok wrote:

>  As part of our internal email management, we generate some of our
>  sendmail config files (local-domains and relay-domains) by querying
>  mx records for each domain.

	But this is based only on the list of domains that you know 
about, right?  You don't just arbitrarily add your machine to the 
list of MXes for a domain if you should happen to find out about this 
domain through some other channel?

>  Obviously, our customer's domain was removed from our local-domains file
>  because our server was not listed in any MX record for their domain.


>  Is this an acceptable way of setting up DNS for a domain?  Their
>  ISP seems to think so.  I got into a strong discussion with their
>  DNS administrator, because I felt that MX records should accurately
>  reflect the actual mail exchangers.  Obviously, he disagreed.

	I think any additional unnecessary hops for mail are inherently 
bad.  There's just one more place for things to get screwed up.  If 
they want to handle mail for this client, they should handle it.  If 
they want to be a backup MX for this client, then they should do so. 
But they shouldn't list themselves as the primary MX and then do 
internal forwarding to your mail servers.

Brad Knowles, <brad.knowles at>


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