Mark;
I tried to respond to your email off list, but it rejected my message with:
Diagnostic-Code: SMTP; 550 5.7.1 <administrator(_at_)yellowhead(_dot_)com>...
Go away,
spammer! [207.34.104.5] (invalid HELO)
You might want to re-examine the criteria you are using, as there is
nothing non-standard about the way our server is configured. The EHLO our
sendmailNT server uses by default is the physical server name <SERVER3>,
and is not configurable using the built in UI. It has passed all SPF checks
that I have run against it.
J.A. Coutts