Using forwarders results in mail server issue.

[Mark_Andrews at isc.org]

> Hello all,
> 
> Inside our company (eds.com) I manage our groups own little domain
> (es.be.eds.com) with bind 8.2.3 on Solaris8.
> We also have sendmail configured for our own domain on a different unix
> server. This mail server handles mail send to domain es.be.eds.com and uses
> the smart relay of EDS (defined in sendmail.cf) to deliver mail to other
> domains. I also have an MX record in our zone file with only our local mail
> server in it. So far so good, everything works.
> 
> Now I wanted to introduce in BIND a forwarder that knows all internet
> addresses. This forwarder is one of the main EDS internet gateways. 
> So I changed named.conf to have:
> options {
> #
> # boot file for authoritive master name server for Berkeley.EDU
> # Note that there should be one primary entry for each SOA record.
> #
> #
>         directory "/var/named";
>         notify yes;
>         forward first;
>         forwarders {
>                199.42.132.115;
>        };
> }; 
> 
> For DNS resolving everything works as expected, internet hosts get resolved
> fine along with the local addresses.
> The problem is that sendmail doesn't deliver mail for eg guy at es.be.eds.com
> anymore. It suddenly uses a relay it got, I suppose, from the foreign
> forwarder i.s.o. relaying the mail itself. I get the feeling that if there
> would have been an option like 'forwarders last' I wouldn't have this
> problem. I know however that this option doesn't exist unfortunately.
> 
> How can we get round this problem? Anyone knows?
> 
> Thanks,
> Guy.

	You just want to disable forwarding in the internal trees.

	zone "eds.com" {
		type master;
		forwarders { /*empty */ };
		...
	};

	Will disable forwarding below eds.com.

	Mark
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at isc.org