Hi everyone-

Thanks for all your input. My final solution was to download and install
the latest Sendmail, but only because I couldn't bear to have spent the
money for the Sendmail book without using it!  Without the book, I
believe I would've tried one of the alternative MTA's.  I did like the
m4 generation of the Sendmail config file however, and all of this is a
learning experience.

For anyone interested, abuse.net has a relay tester that tries all sorts
of SPAM tricks to get your server to relay/accept a spam message, 17
tests in all.  It is located at:

http://www.abuse.net/relay.html

Again, thanks for all the help!

John P.