[Greylist-users] A Greylisting idea. (fwd)

Evan Harris eharris at puremagic.com
Sun Jun 22 15:46:16 PDT 2003

Forwarded to the list...


---------- Forwarded message ----------
Date: Sun, 22 Jun 2003 11:43:22 -0700 (PDT)
From: Eric J Schwertfeger
Subject: A Greylisting idea.

I read your paper and I like the idea, and was in fact thinking of
implementing a simplified version of it before I saw your paper.

I do have two ideas that may handle your caveats.

First, lists.  There's a perl module which is quite effective at
determining if an email came from a list by examining the headers.
Admittedly, you won't have the headers the first time an email is
delivered, but you can have the MTA detect it on retry, and have the
milter module add a wildcard entry permanently whitelisting that mailing
list.  Adding wildcards to the database shouldn't be hard, just do it in
the sendmail method and have the first lookup check for
"fromfield IN ('senderuser at senderdomain",'@senderdomain')".  Does that
make sense?  In the case of several lists hosted at the same domain, one
entry could whitelist all of them (wouldn't want to do that for Topica
lists or such, though, but that's O.K. as the module will tell you the
software that is used to send out the list, in most cases).

Second, the MTA that blows out if all the RCPT TO:s fail:  What MTA is
that?  I've only seen spamware fal own that way.  Have you considered
having the milter code override the error code if RCPT TO:s failed?  Is it
even possible to do this using the milter interface?

Gotta run, hope this input helps.

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