Trying to send external mail to a local sendmail box

[Lars Hecking]

 This looks rather like a routing or fw setup problem to me. Does your
 gateway actually receive external SMTP requests? Does it accept them?

 If your gateway is an actual Unix machine, I get rid of the DNS alias
 and route the mail directly to ion by mailertable or transporttable.

nsyte writes:
> I need some help. I am running sendmail on a local machine
> (ion.somedomain.com) separated by a packet filtering firewall
> (gateway.somedomain.com), and I have an external DNS (authoritative for
> somedomain.com). The DNS MX records point to gateway; gateway forwards
> all port 25 traffic to ion.
> 
> Because the mail servers of the world will not accept mail from a non-
> existent host, I set up the external DNS records to alias ion to
> gateway. Now I can successfully send mail out.
> 
> I can telnet to port 25 of ion and manually construct a mail session;
> however, when I address mail from an external client to
> user at somedomain.com or user at ion.somedomain.com, I get the messages
> below.
> 
> It does not appear that the mail is getting past gateway. Do I have the
> DNS set up correctly? I cannot point the MX records to anything besides
> gateway. It should forward mail traffic to ion, right?
> 
> Where is the problem?
> 
> Thanks for your help.
> 
> 
> ---------------------------------------------------------------
> (to user at ion.somedoman.com)
> 
> The original message was received at Sun, 12 Mar 2000 01:29:46 -0600
> (CST)from ccis01.baylor.edu [129.62.1.18]
> 
>    ----- The following addresses had transient non-fatal errors -----
> <user at gateway.somedomain.com>
> 
>    ----- Transcript of session follows -----
> <user at gateway.somedomain.com>... Deferred: Connection timed out with
> gateway.somedomain.com.
> Warning: message still undelivered after 4 hours
> 
> ----------------------------------------------------------------------
> (to user at somedomain.com)
> 
> The original message was received at Sat, 11 Mar 2000 14:26:50 -0600
> (CST) from ccis01.baylor.edu [129.62.1.18]
> 
>    ----- The following addresses had transient non-fatal errors -----
> <user at somedomain.com>
> 
>    ----- Transcript of session follows -----
> <user at somedomain.com>... Deferred: Connection timed out with
> gateway.somedomain.com.
> Warning: message still undelivered after 4 hours
> Will keep trying until message is 5 days old