OK; there was a brief window where I was close enough to grab the configuration. I've redacted my userid and password.
Note this is -current, there were syntax changes to the configuration file in late January.
Code:
$OpenBSD: smtpd.conf,v 1.6 2013/01/26 09:38:25 gilles Exp $
listen on lo0
listen on rl0
table aliases db:/etc/mail/aliases.db
table myauth { userid => userid:password }
accept from any for local alias <aliases> deliver to mbox
accept from any for domain "jggimi.homeip.net" alias <aliases> deliver to mbox
accept for any relay via \
tls+auth://userid@outbound.mailhop.org auth <myauth>