I finally went against the geek in me and ditched sendmail from our internal mail server and moved to the simpler Postfix. The reason being that I simply couldn’t figure out how to configure sendmail to send mail to another server as a relay. Seems so simple and I even read the bat book to try to figure it out, but was unsuccessful. Postfix did it with one configuration setting.
Fetchmail still pulls down our mail from our public mail server to our internal server and it worked without a hitch with Postfix. And Postfix was amazingly easy to install, it even makes itself a replacement for sendmail by aliasing the sendmail binaries to itself. I wish I’d done this years ago!