Yalla-One: I'm just reading your thread here because I need to learn too. If I understand your original question, you basically want to have one pc on your lan, receive mail from other pc's on your home lan, and be able to send out to the internet? I'm lost at the smart host stuff OMG, 7 months now in linux and I just learned how to get mail for root I'm slow I know. But if you send out to the internet, don't you have to go thru your ISP's server's so that you don't get marked as spammer? That's one thing that confuses me too because my ISP uses SSL 995 ports and stuff and...ugh Anyway I look forward to you writing up what you did.

Yalla-One + fakie_flip, you need to remove "dnl" from the beginning of the line at put it at the end. The 'dnl' string in the .cf file means the same thing as # or // in every other language: end-of-line. Just look at the lines at the end of /usr/share/sendmail/cf/cf/sendmail-slackware.mc

I know it's a year late, maybe it will help someone.