> > The number of subscribers just max out our UNIX sendmail. We are
> > experimenting to use NT LSMTP to diliver our UNIX Listserv mail.
>
> You could also try qmail, http://www.pobox.com/^djb/qmail.html,
> currently at version 1.00.  It has a secure design, runs quite fast on
> Unix systems, delivers mail reliably, etc., and it's free.  At least one
> LISTSERV site is using it to make ^600,000 deliveries a day.
> --
>   Norm

If you are thinking of using qmail, you should be aware that it has
some differences from sendmail and other SMTP implementations that may
be important to you.  I don't have personal experience with qmail, I've
just been around for some of the discussions in some of the IETF email
groups among Dan Bernstein, author of qmail, and others.

One difference is that qmail apparently always sends a separate copy of
a message to each recipient and may open up many connections in
parallel to do this.  While this does not matter much for the ordinary
Internet mailing list and might well make for faster delivery in common
cases, it might bite you if you have a mailing list (as we do) with
hundreds or thousands of subscribers on a small number of hosts.

Also, I don't think that qmail generates bounces in the Internet
DSN format that can be automatically interpreted by LISTSERV.

Anyway, check out the differences if you are thinking of switching.