You can't run two SMTP products on the same machine unless one of them
can forward mail to the other one on a non-standard port.  Exchange
cannot (as far as I know) do that, and the SMTPL "listener" service
is strictly a "dumb" SMTP server--it accepts mail only for LISTSERV
and for the lists on the machine (it can't relay).

Similarly, under NT, if there is no way to get the mail via MAPI from
Exchange to LISTSERV in a format LISTSERV understands (the Base64 JOB
format you've probably noticed), again, you can't get this to work.
And no such "connector" service for Exchange is available, so it isn't
possible.

What you are doing is the standard way to run LISTSERV when you do not
use LSMTP for a true "turnkey" solution (where everything is on the same
machine and LISTSERV can run without reliance on a separate SMTP server
for outgoing mail).

Nathan