What MDA are you using? Where is the last line normally in the stock mc file that calls MAILER(procmail)?

Sorry, but I don't understand the question. The original sendmail-slackware.mc file has the last line "MAILER(procmail)". I assume that means it is using procmail as the MDA?

You answered the question. The reason I asked is because you posted your mc file earlier in the thread and that line was missing at the end. I'm confused why your email is not showing up in /var/spool/mail/user_name.

Looks like I just missed that line when I copied the text. It's there in my .mc file, and it is the last line.

Do I need to specify which port to listen on? (ex. "DAEMON_OPTIONS(`Port=smtp, Name=MTA')" is in the default sendmail-slackware-tls.mc file)?

Not unless you want to run on a non-standard port. You should be able to nmap your server and see if its listen on port 25. The fact that I mention this gives me pause. Running an email server successfully is not rocket science but it does require enough understanding to prevent open relay abuse. You don't want to learn the hard way!

^^ Exactly why I want to run a mail server: for the learning experience. You could put a book in front of me and tell me to read it, and I wouldn't pick up most of it, but rather I learn (mostly) from experience.

Anyway, it turns out that it was not in fact listening on _any_ port. I used netstat (learning real troubleshooting! yay!) and put in "DAEMON_OPTIONS(`Port=smtp,Addr=[LAN IP], Name=MTA')" into the .mc file. now netstat -a gives I'm still looking at a closed port 25 somewhere though. Hrm.

EDIT: nmap shows that port 25 is open on the local machine.