smtpd receives mail and stores it (sendmail -bd replacement)
smtpfwdd passes it to sendmail or can relay to another machine
Pretends not to be OpenBSD ("4.1 SMI" :-)
Runs in chroot jail /var/spool/smtpd
Another hand-drawn table, which isn't here.
Part of the value-add for paying to attend the tutorial. :-)