internal Windows smtp server sending to Exchange local domain

Posted on 2011-04-18
Last Modified: 2012-05-11
I've got an Exchange 2003 server (EXCH03) in an Active Directory domain (InternalDomain.local) that is responsible for an internet domain name (

I have another server (UTILITY) in the network that is joined to InternalDomain.local, and runs SMTP as a mail server for some miscellaneous processes (e.g., a NAS box has SMTP settings pointing to UTILITY for unauthenticated relay).  

The SMTP service has no problem sending mail to external recipients.

The UTILITY server does not forward mail to the Exchange server for local users with the internet domain as the recipient address.  There is no Domain listed in IIS on UTILITY for (only InternalDomain.local).

I have split dns for, with an MX record on the internal zone pointing to the Exchange server, and nslookup from UTILITY successfully finds the MX.  The messages simply sit in the Queue folder on UTILITY.

The NAS is set to send mail to (external) and to (my address on the Exchange server).
The SMTP log on UTILITY shows the mail come in from NAS for each rcpt.
There is an outgoing smtp for
There is no connection (in the smtp log) to EXCH03 for

Question by:snowdog_2112
    LVL 3

    Expert Comment

    You'd should configure Exchnge smtp capability 1st
    Please read
    and ask if you do'nt understange smth

    Accepted Solution

    I did not have an MX record correct on the internal split DNS zone for my public domain name.  The second stmp box was trying by first doing an MX lookup, but does not get an MX, so there was no smtp connection to the Exchange server!

    Duh!  I should have seen that sooner.

    Author Closing Comment

    Internal split DNS zone for the public domain needs an MX record for other smtp servers on the inside network to send mail to your Internet domain name using the internal Exchange server.

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