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Verify DNS records for owa and mail A records - email not being delivered

jsvor asked
Last Modified: 2012-05-05
I have been contacted by an admin from a local company saying that they are not able to send mail to our domain.com email addresses.  They receive an NDR eventually that says the following:

The following recipient(s) could not be reached:

      user@domain.com on 3/24/2007 11:13 AM
            The e-mail system was unable to deliver the message, but did not report a specific reason.  Check the address and try again.  If it still fails, contact your system administrator.

            < s001.OTHERDOMAIN.COM #4.0.0 X-Postfix; lost connection with    mail.domain.com [] while performing the initial protocol    handshake>

The admin says that their Sophos mail server shows logs that the mail is trying to be delivered to owa.domain.com instead of mail.domain.com.  He thinks that my DNS settings for domain.com are not setup correctly and thinks I need to fix it.  I have not heard of any other complaints from other companies not able to contact us via email.  

I am trying to determine if my DNS settings are correct for my setup or if I need to change them.  Since I have the same IP set for owa.domain.com and mail.domain.com the admin believes I need to obtain another IP address from my ISP and set owa.domain.com to it.  Is that necessary?  Let me know if you need any more information.

I have a setup as follows:

Public IP:
domain: domain.com

-Small office with SBS 2003, using Exchange for domain emails - domain.com.  The Exchange server is setup for OWA from the external network so that users can access their mail by going to https://owa.domain.com/exchange.  
-Windows 2003 Server with ISA Server 2006 as firewall connected directly to internet connection.  Port 25 is opened and forwarded to SBS server for mail delivery.  Traffic for owa is also forwarded to SBS server.

-------DNS Records---------
Subdomain: .
Type:  NS
Value:  ns1.s422.sureserver.com
TTL:  25920

Subdomain: .
Type:  NS
Value:  ns2.s422.sureserver.com
TTL:  25920

Subdomain: owa
Type:  A
TTL:  14400

Subdomain: .
Type:  A
TTL:  14400

Subdomain: *
Type:  A
TTL:  14400
Subdomain: mail
Type:  A
TTL:  14400

Subdomain: .
Type:  MX
Value:  mail.domain.com
TTL:  14400

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