get local sendmail to use MX records

Gerard Meijer gmeijer at
Thu Feb 24 08:05:01 GMT 2005

I'm 100% sure this is not the case and here is why. I figured something out.

All my servers do the same thing. It has something to do with the reverse 
DNS pointers of some domains.

For example. I have (another) server running with 20 domains under 4 ip 
addresses where I never ever touched sendmail or its configuration files. 4 
of the domains have a reverse DNS pointer to one of the 4 ips. Sendmail 
handles 16 domains well (= looks up MX records and delegates the mail to the 
right server) and tries to handle the mail of 4 domains itself. Needles to 
say that those 4 domains are the ones that have reverse pointers to the 4 
ips attached to that particular server.

I tested this on 5 servers and its the same everywhere.

I hope one of you knows what to do with this information. I spotted the 
problem now, but I don't know how to solve it. Clearly sendmail prefers a 
reverse pointer to a domain above looking up the MX records and using them, 
but how can I let it stop doing that?

----- Original Message ----- 
From: "Ted Mittelstaedt" <tedm at>
To: "Gerard Meijer" <gmeijer at>; "Greg Barniskis" 
<nalists at>
Cc: <freebsd-questions at>
Sent: Thursday, February 24, 2005 8:49 AM
Subject: RE: get local sendmail to use MX records

>> -----Original Message-----
>> From: owner-freebsd-questions at
>> [mailto:owner-freebsd-questions at]On Behalf Of Gerard Meijer
>> Sent: Wednesday, February 23, 2005 2:08 PM
>> To: Greg Barniskis
>> Cc: freebsd-questions at
>> Subject: Re: get local sendmail to use MX records
>> I really don't understand it at all now.
>> I emptied my virtusertable and local-host-names files. I
>> really don't know
>> why this happens.
> Did you look in your mailertable file?
> You have listed in one of your sendmail config files, that is
> the only explanation.  Or you have it in /etc/hosts.  or in /etc/rc.conf.
> it's somewhere.
> It is problems like this is why when your running commercial servers
> that you create build sheets for each server.  That is, you record on
> a separate document EVERY configuration step of any significance that
> you or anyone else does.  Sorry you had to find this out the hard way.
> You probably have secreted in some hack you forgot that you
> did.  Maybe one of these days when you do a nuke and repave you will
> remember to start a build sheet.
> Ted
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