Question : australia emails are bouncing

I am not even sure what to ask, so i am going to see if i can give enough info

I have a linux box that sends out emails to our users
this box is configured to sendmail via our mail server
snippet from sendmail.mc
define(`SMART_HOST',`mail.mydomain.com')

the program that sends the email sets the from to be [email protected]

but for some reason the ISP os trying to connect to ns1.mydomain.com for some kind of verification. (ns1.mydomain.com is the box where the email is coming from)

ns1.mydomain.com is behind a firewall and all email goes through our email server

here is the bounce

====================================================================

-----Original Message-----
From: [email protected]om [mailto:[email protected]domain.com]
Sent: Tuesday, February 03, 2009 12:50 PM
To: [email protected]
Subject: Undeliverable Mail

Delivery failed 10 attempts: [email protected]

RCPT TO generated following response:
450 4.7.1 ... recipient denied, because MX 0 'ns1.mydomain.com' [xxx.xxx.xxx.20] for not answering

Original message follows.

Received: from ns1.mydomain.com [xxx.xxx.xxx.20] by mail.mydomain.com with ESMTP
  (SMTPD-10.02) id A35B01C8; Tue, 03 Feb 2009 10:39:55 -0600
Received: from ns1.mydomain.com (localhost.localdomain [127.0.0.1])
      by ns1.mydomain.com (8.13.7/8.13.4) with ESMTP id n13Ge74W002688
      for ; Tue, 3 Feb 2009 10:40:07 -0600
Received: (from apache@localhost)
      by ns1.mydomain.com (8.13.7/8.13.7/Submit) id n13Ge6Wg002687;
      Tue, 3 Feb 2009 10:40:06 -0600
Date: Tue, 3 Feb 2009 10:40:06 -0600
Subject: [mydomain.com #53406] your email re changes
From: "Josh via RT" >
Reply-To: [email protected]
In-Reply-To: 4A026E9@JanSmithPC>
References: com> 4A026E9@JanSmithPC>
Message-ID: -1297.53406-6-0@mydomain.com>
Precedence: bulk
X-RT-Loop-Prevention: mydomain.com
RT-Ticket: mydomain.com #53406
Managed-by: RT 3.4.4 (http://www.bestpractical.com/rt/)
RT-Originator: [email protected]
To: [email protected]
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 8bit
X-RT-Original-Encoding: utf-8


MESSAGE BODY WAS HERE


> [[email protected] - Tue Feb 03 07:01:58 2009]:
>
> This transaction appears to have no content
>

-------------------------------------

thanks for any help
Randy

Answer : australia emails are bouncing

It looks like your mx record is set wrong.  It has the highest priority MX pointing to ns1.mydomain.com.  To fix this either 1) allow connections to the smtp server on port 25, or 2) change the MX record so it points to the actual mail server.