[lug] Screwed up inbound email (and DNS)

[John Hernandez]

IIRC, some MTA's will send mail to an A record address if no MX record 
is available, while others just barf.  You'll need to make an MX record 
available to reliably receive mail.

A related problem seems to be that you don't currently have a clean 
division of your internal vs. external IP address space vis-a-vis DNS. 
  You might consider implementing a "split DNS".  For example, you can 
have your registrar maintain your public (externally visible) DNS which 
only offers "routable" (public) addresses; then use an internal server 
(or just /etc/hosts in a simple environment) for the 192.168.x.x 
private stuff.

Under the current arrangement where your only externally announced 
nameserver dog.hardiman.com is on private space, nobody can resolve 
names (including MX records) for your domain, with the exception of the 
two A records listed with your registrar (dog and netwolf).  There's no 
sense in telling someone out on the Internet that dog.hardiman.com is 
at 192.168.0.2, because it can't be reached.

The book "Firewalls and Internet Security" explains this in more 
detail.  There may also be some HOWTO's floating around the net.

-John

Paul Hardiman wrote:

> Hi,
> As the subject implies, I have a slight problem at hardiman.com.
> I have added a dsl router and updated my dns and MTA (exim).
> I am getting a trickle of inbound email into hardiman.com, but not 
> getting mailing list
> traffic such as from this list (hence the alternate email account in the 
> from line).
> I check the router's port log and I see mostly dns (port 53) traffic, 
> but verly little smtp (25).
> 
> I do have an MX record pointing to the MTA host, with port forwarding 
> (smtp, et al) to the same host. However, the MX record is not visible 
> outside my domain. Is this a problem?
> If so, how does one proceed?
> Is the MX record overkill for a small domain (1 zone)?
> 
> Appreciate any assist.
> 
> Regards,
> Paul Hardiman
> 303-581-0006
> 
> 
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