sendmail MX config magic.

[Rodney Thayer]

I had to do the following to get sendmail to work.  What this does is to make
it legal for my host running sendmail to receive mail from another host, 
where the domain name system says the other host is one of my host's MX 
entries.

Here's the make command:

  make -f Makefile.Linux ENVDEF=-DNOLOOPBACKCHECK LIBS=-ldbm