Summary: secure Free SMTP relay?

[Neale Banks <neale () lowendale com au>]

I asked:

> What are the current Free choices for a "secure" (Ok, this is a relative
> judgement ;-) SMTP relay daemon to run under Linux?
>
> Looking around, if one eliminates Sendmail, smail etc as too big (and
> hence "risky") this leaves smap (non-Free) and the likes of qmail and
> postfix. Or have I missed something else?

and received quite a few off-list replies.  Summary follows...

> Are we talking Free Beer or Speech?

I should have been clearer: preferably both ;-)  Ideally something that
can be easily bundled in to a solution being "sold" to a client.  Even if
a "commercial" licence were not many $, it's a hassle to organise it if
there is an equivalent "Free" alternative.

Three people suggested smap, which is part of the fwtk
<URL:http://www.fwtk.org>.  While probably a technically good answer,
licensing is required for "commercial" redistribution.

Two suggested smtpd (part of the Juniper Firewall Toolkit by Obtuse
Systems <URL:htp://www.obtuse.com>).  This used to be covered by a
similarly restrictive licensing arrangement but is now "Open Source" and
the license appears to qualify as "freely resditributable".  On the
downside, it requires an SMTP MTA to deliver the mail.

exim <URL:http://www.exim.org> and zmailer <URL:http://www.zmailer.org>
were suggested by one and two people respectively.

Surprisingly, postfix <URL:http://www.postfix.org> and qmail
<URL:http://www.qmail.org> received only two and one recommendations
respectively - I expected that these would have received more comment as
they were both written specifically with security as a major design
consideration. OTOH, they were the only ones to receive negative comments
- one correspondent cautioned that postfix might be too immature and
another critised qmail's source code style (touchy issue?).

All things considered, my shortlist looks like postfix, qmail and smtpd.

I'll look closer at postfix first.

Thanks to all who replied,
Neale.