Daniel Bromberg:
> The discussion over the invalid space syntax got me thinking, so I
> tracked my SMTP traffic for about 45 minutes. The only non-compliant
> clients were clear spammers, save for two gray-area clients, one using
> StrongMail <http://www.strongmail.com/> -- surprise, surprise a purveyor
> of mass marketing software, and the other also a mass-marketing, if
> legitimate, campaign. (Sorry, [email protected], [email protected],
> and [email protected], but thou doth giveth thyself away.)
>
> Is this a useful option to add to _postcreen(8)_? I can't find anywhere
> postscreen can classify anything as "meeeh" rather than accept/reject,
> but from a few hundred samples (admittedly, quite small), this is a 100%
> mass-marketing-positive classifier.
Postscreen answers one YES/NO question: is this client allowed to
talk to a Postfix SMTP server process. It makes this ruling on
the basis of a single SMTP connection. Spambots rarely come back.
Currently, some 90% of mail is spam, some 90% from zombies. If
you believe that address syntax checks will catch a significant
fraction of that, then it would be something to consider in
postscreen.
Right now, postscreen's most effective measures are DNSBL, pregreet
detection (over 55% of spambots on my server trigger this defense),
and detecting clients that connect to the backup MX only (some 10%
of spambots on my server trigger this defense).
Everything else can easily be stopped with non-postscreen features.
Wietse
