On Tue, Apr 17, 2007 at 08:40:30PM +0200, Tomasz Chmielewski wrote:
> Gary V schrieb:
> (...)
> > If used as an after-queue filter it's simply too late in the process.
> > As far as Postfix is concerned it has accepted the message and is now
> > responsible for it. Even if amavisd-new D_REJECTs it at this point
> > Postfix would be obligated to create a bounce notice. This is just what
> > you are trying to avoid (and is an argument for the use of D_DISCARD
> > for spam and viruses). It's actually an argument for using amavisd-new
> > as a before-queue filter but as we have discussed, doing so is not
> > recommended or supported.
>
> Of course, before-queue filtering will only work properly if we have
> enough processing power available to filter the mails before the SMTP
> connection times out.
>
>
> Greylisting we know today has many advantages:
> - it makes lot of spam not delivered
> - as a result, it offloads mail/filter servers from content filtering
>
> It has a big disadvantage: it introduces delay in mail delivery.
>
> As I checked my mail server's stats, with greylisting applied to each
> and every incoming message,
That's not by any means a necessary implementation. Applying
graylisting only to *servers* (IP addresses) rather than the
server+sender+receiver tuple that some recommend, means that any
server from which you receive legitimate mail will rapidly enter the
non-delayed IP set and thereafter will experience no delays.
An alternative application of your core idea would be to count a
server IP address as successfully un-graylisted (i.e. enter it into the
DB) only when it delivers a mail which passes amavisd as non-spam.
This could be done "behind" amavisd in an after-queue deployment.
-- Clifton
--
Clifton Royston -- [EMAIL PROTECTED] / [EMAIL PROTECTED]
President - I and I Computing * http://www.iandicomputing.com/
Custom programming, network design, systems and network consulting services
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