addendum:

I've been experimenting with some of my other "working" installs of courier
and I've discovered that if I'm connecting from an IP other that the one(s)
listed in my "/usr/lib/courier/etc/smtpaccess" and use that server as my esmtp
server then the mail gets bounced. (i.e. 513 Relaying Denied.)... which I guess
makes sense because I'm trying to "relay" mail through that server, right? So my question IS, what happens if I'm using dial-up or something with a
changing IP? Do I need to add every IP (or range of IP's) that the user -might-
be connecting from to my "/usr/lib/courier/etc/smtpaccess" files? - Isn't there
a way to authenticate the user, say using IMAP/SSL, and then grant them the
ability to use the server to send mail?