sendmail "accept unresolvable domains" issue

[Frank Cox <theatre sasktel net>]

I just physically moved a mailserver across the street to a new office, and
also moved it onto a different ISP.

I changed /etc/resolv.conf to the new ISP's dns servers.

Suddenly I can't receive any mail from anybody.

sendmail[3380]: n2V6Sw4k003380: ruleset=check_m
ail, arg1=<ltsp-discuss-bounces lists sourceforge net>, relay=[142.165.72.21], r
eject=451 4.1.8 Domain of sender address ltsp-discuss-bounces lists sourceforge 
net does not resolve

And so on.  Everything is rejected with a 451 4.1.8.

I uncommented "dnl  FEATURE(`accept_unresolvable_domains')dnl" in sendmail.mc,
and now I can receive mail again.

I can dig any mx record from that server without any problem and I can send
email out to anyone without problem too.

So what did I not change?  It worked fine before as it was, and as I said, all I
did was move the machine across the street, give it a new IP address and
edit /etc/resolv.conf.  In fact, I didn't even give the actual machine a new
address. It lives behind a router and all I had to do was give the router the
new WAN address.

-- 
MELVILLE THEATRE ~ Melville Sask ~ http://www.melvilletheatre.com