Internal Mail DNS questions
Kevin Darcy
kcd at daimlerchrysler.com
Sat Jul 2 01:56:44 UTC 2005
AVB wrote:
>I am having trouble sending mail internally from Server2 to Server1.
>Server2 sends mail fine to any other domain but just not internally.
>Server1 is our main Mail server and Server2 just sends message from our
>database application. Both servers are on the same W2K subnet and
>domain and I have one DNS server only for the internal machines. Our
>internal domain name is different than our Mail Domain name too so I'm
>not quite sure how MAIL DNS Queries operate in this regard.
>
>I set up both domain names in our internal DNS server with a MX and A
>record for the main mail server (server1) in the external domain and
>when I run
>
>Nslookup -q=mx server1.externaldomain.com I get:
>server1.externaldomain.com 192.x.x.x (internal IP)
>
>if I run NSlookup -q=mx externaldomain.com I get:
>responsible mail addr = admin.internaldomain.com
>
>if I delete the external domain in our internal dns server and run
>nslookup -q=mx server1.externaldomain.com I get the correct external IP
>
>and if I run nslookup -q=mx externaldomain.com I get the correct
>server1.externaldomain.com and IP
>
>Not sure how to succesfully set up the DNS server for this. Anyone have
>any thoughts? TIA!
>
What makes you think that your database app is doing MX lookups at all?
Usually mail-enabled apps either a) deliver an SMTP message directly to
a pre-configured SMTP server, or b) submit the mail message to the local
mail subsystem (e.g. sendmail, Postfix), and let that subsystem take
care of delivering it. Whether that subsystem uses MXes for routing its
mail, or some other method, is entirely up to the how the MTA is
configured, and not really on-topic for this list.
As a DNS note, however, the "responsible mail addr" you show above is
probably the RNAME field of an SOA record you got in the Authority
Section of an NXDOMAIN response. I think you're getting it confused with
an actual MX target. Using "dig" instead of "nslookup" would probably
help to clarify this kind of stuff.
- Kevin
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