sendmail as a secondary MX

[Janet Sullivan]

Janet Sullivan wrote:
Could it be that sendmail is seeing the domain names in rDNS for the 
servers IPs, and deciding that they are local, even if they are set in 
the relay-domains file?
	
That's IT!!!  Hot damn, I found it.
Let's take poohmail.org as an example.  It has its MX records set like so:

                IN      MX 10   nj.bgp4.net.
                IN      MX 20   tx.bgp4.net.
poohmail.org is listed in /etc/mail/relay-domains.

The tx.bgp4.net box has 8 IP addresses assigned to it.  Even though 
poohmail.org is not the host name of the box, it is the rDNS for one of 
the IPs.

As long as sendmail sees that one of the IPs reverses to poohmail.org in 
DNS, it refuses to treat it as a relay domain, but insists its local.

I put in a bogus hosts entry to stop sendmail from seeing the rDNS for 
poohmail.org.  Once I restart sendmail it now acts as a secondary for 
the poohmail.org domain just like I expected it to.

Either this behavior is unique to DF sendmail, *or* the sequence and 
timing of the start up is different enough from FreeBSD to make a 
difference.  Perhaps in FreeBSD, sendmail started up early enough that 
it couldn't resolve the rDNS entry for all the IPs on the box?!

At any rate, that's the issue.  I don't know why FreeBSD let it work, 
and not DF, but hey...