I was trying to figure out how to just send email from my iMac. I didn't need to receive mail on the mac. It was originally motivated by trying to send mail from PHP, but there are other cases when I wanted to send mail from a shell script. Either way, I needed to be able to invoke sendmail to relay to a SMTP server.
I tried setting the smart relay host, DS, which usually works on most Unix machines. But it wasn't working. I eventually realized that the NetInfo tweaking referred to in the article was needed, even if I wasn't running a server.
Before I figured that out, I created a minimal sendmail.cf file that uses the nullclient FEATURE. This might be of use to others, so here it is:
VERSIONID(`$Id: generic-darwin.mc,v 1.3 2002/04/12 18:41:47 bbraun Exp $')