Problem with MX records behind firewall.

[Alan Chandler <alan@chandlerfamily.org.uk>]

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I have a netgear firewall/router that allows portforwarding of specific ports 
to my internal network.

If I send mail to chandlerfamily.org.uk the MX record on the external DNS for 
this is the external address of my netgear box, but attempts to access its 
smtp port will cause all connections to be forwarded to an internal machine 
on my network (10.0.10.100) using NAT addressing and port forwarding.

I am having a problem with Mailman on my internal network with the 
chandlerfamily.org.uk mail addresses.  My guess is its doing an MX lookup and 
getting the external address of my netgear box.  Unfortunately, the 
port-forwarding does not seem to work when accessing the box from internally.  
So the net effect is that mailman gets told that this mail address is 
invalid.

One thing I could do, since I am running bind as a dns server on my internal 
network is to create a zone file for the chandlerfamily.org.uk domain with MX 
records pointing to the internal IP address.

Is this possible (since only internal machines will be querying that 
particular DNS) as the domain will be defined differently that the public DNS 
with my domain in it?  Can I set it up this internal DNS to only hold a 
subset of my domain and somehow forward the requests it can't answer on to 
the public DNS?

 
- -- 
Alan Chandler
alan@chandlerfamily.org.uk
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