[exim] Detecting the Registrar Barrier

OK - I think I'm making some progress on this. I created a DNS server
that you can pass a $sender_host_name to and get a code indicating if
it's a one level or 2 level domain.

I still have more work to do to make it practical. But - try this out
and tell me if I'm on the right track.

from your command line run:

dig <host>.rb.junkemailfilter.com

Example:
dig ftp.perkel.com.rb.junkemailfilter.com

It will return a 0.0.0.1 for single level domains and a 0.0.0.2 for two
level domains.