Sendmail mystery

[Stuart Biggerstaff]

Thanks, David.

Of course that sounds exactly right, but we have an MX in the zone file.
And the box is (or should be) looking to itself for DNS

$ttl 38400
lindahall.org.	IN	SOA	www.lindahall.org.
support.lindahall.org. (
			1071778405
			10800
			3600
			604800
			38400 )
lindahall.org.	IN	NS	www.lindahall.org.
lindahall.org.	IN	MX	1 descartes.lindahall.org.
leonardo.lindahall.org.	IN	A	192.168.101.101
descartes.lindahall.org.	IN	A	10.1.101.113

We had tried to keep it as simple as possible, as we only really need a
caching name server for these systems, but for need to access the mail
server.  Which was previously in the DMZ with these systems, but is now
inside (thus the different subnet).
 

Stuart Biggerstaff
Systems Technician
Linda Hall Library of Science Engineering & Technology
5109 Cherry St.
Kansas City, Missouri 64110-2498

Phone:	(816) 926-8748
	(800) 662-1545 x748
FAX:	(816) 926-8790
URL:	www.lindahall.org 
-----Original Message-----
From: linux-users-bounces at linux-sxs.org
[mailto:linux-users-bounces at linux-sxs.org] On Behalf Of David Bandel
Sent: Tuesday, February 20, 2007 2:09 PM
To: Linux tips and tricks
Subject: Re: Sendmail mystery

On 2/20/07, Stuart Biggerstaff <biggers at lindahall.org> wrote:
> We just moved our mail from a server in our DMZ to a new one which is 
> internal with some NAT rules.  Mostly everything is working, but we 
> have some automated e-mail (a couple of web forms, and sending copies 
> of
> logs) being sent from two web servers to accounts on the mail server, 
> and that sort of fails.
>
> The old mail server was providing DNS for things in our DMZ, and we 
> have moved that to our main web server.  After a lot of editing of 
> configuration files and changing rules on our firewall, sending mail 
> from the web servers works, after a fashion.  That is, it queues to be

> sent, and when we flush the queue they go.  Maillog shows the messages

> deferred because Sendmail was receiving a host name lookup 
> failure--when accessing the new mail server for DNS.
>
> Our initial configuration used the old mail server for DNS, while the 
> new one is supposed to use the web server itself.  The only place I 
> have entered the name or IP of the new mail server is in /etc/hosts 
> and in the configs for BIND, but nowhere as a name server.
>
> Anyone have a suggestion where to start looking?
>

Stuart,

Your problem is that mail servers query DNS for an MX address.  In case
you hadn't noticed, /etc/hosts only provides the equivalent of an A RR
(or AAAA RR in case of IPv6), but not an MX RR.  You need to provide a
DNS entry with an appropriate (prioritized) MX RR.  Until then, you will
have problems.

Ciao,

David A. Bandel
--
Focus on the dream, not the competition.
            - Nemesis Air Racing Team motto
_______________________________________________
Linux-users mailing list ( Linux-users at linux-sxs.org )
Unsub/Password/Etc:
http://mail.linux-sxs.org/cgi-bin/mailman/listinfo/linux-users

Need to chat further on this subject? Check out #linux-users on
irc.linux-sxs.org !