secure Free SMTP relay?

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

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?

Thanks,
Neale.