dccifd / greylisting problems

[Smart,Dan]

That's exactly how the dcc greylist is implemented, as a sendmail milter.
For postfix, you must use a postfix policy server, such as Postgrey.  There
is no policy server integration for DCC to Postfix
(http://isg.ee.ethz.ch/tools/postgrey/).

<<Dan>>




>  -----Original Message-----
>  From: MailScanner mailing list
>  [mailto:MAILSCANNER at JISCMAIL.AC.UK] On Behalf Of Mariano Absatz
>  Sent: Tuesday, August 03, 2004 10:08 AM
>  To: MAILSCANNER at JISCMAIL.AC.UK
>  Subject: Re: [MAILSCANNER] dccifd / greylisting problems
>
>  On Mon, 2 Aug 2004 10:46:57 -0500, Smart,Dan
>  <smartd at vmcmail.com> wrote:
>  > PMJI:
>  > The negative of greylisting is that some "legit" mail
>  servers may give
>  > up after one attempt.  These will need to be whitelisted
>  to bypass greylisting.
>  >
>  > Also, there is a long discussion on DCC list on
>  functionality, and it
>  > appears that an initial denial of 1 - 3 minute(s) is sufficient to
>  > stop most Spam senders, who send once then forget.  Most
>  users would
>  > not see this delay.  Whitelisting will still be an issue
>  for broken sites.
>  >
>  > Greylisting needs to run at the mail MTA, so that messages
>  get blocked
>  > *before* they are accepted by your mail MTA.  That's the
>  whole idea...
>  > Block messages once before accepting them the second time.
>  >
>  > Each message records a tuple in DCC:  The sender,
>  recipient, and IP
>  > address of sending MTA.  After being saved the first time,
>  every time
>  > this recorded tuple is seen, the message gets delivered
>  immediately.
>  > The tuples have a time-to-live, and will expire off the
>  DCC server eventually.
>  >
>  > <<Dan>>
>  >
>  >
>  >
>  >
>  > >  -----Original Message-----
>  > >  From: MailScanner mailing list
>  > >  [mailto:MAILSCANNER at JISCMAIL.AC.UK] On Behalf Of Matthew Henkler
>  > >  Sent: Saturday, July 31, 2004 10:03 PM
>  > >  To: MAILSCANNER at JISCMAIL.AC.UK
>  > >  Subject: Re: [MAILSCANNER] dccifd / greylisting problems
>  > >
>  > >  On Sat, 31 Jul 2004, John Rudd wrote:
>  > >
>  > >  > But I think it's more of a sendmail milter type thing
>  than a  >
>  > > mailscanner thing.  By the time mailscanner sees the
>  message, it's
>  > > too  > late to reject it for the sender to try again later.
>  > >
>  > >  Yes, that seems likely now that I think about it.  The
>  way I  have
>  > > it set up at least, it is  most likely too late for
>  MailScanner to
>  > > do anything about.  Guess I'll have to play  around with
>  it at the
>  > > MTA level.
>  > >
>  > >  Good explanation of greylisting for everyone though, thanks!
>  > >
>  Anyway... greylisting CAN NOT work within MailScanner.
>  Graylisting has to be done during the incoming SMTP dialog
>  and must choose to accept or temporarily reject (errcode
>  4XX) a given SMTP transaction.
>
>  MailScanner runs AFTER the SMTP transaction is over so
>  there's no way that you can do graylisting within it.
>
>  Maybe it could be implemented in a milter for sendmail, I dunno.
>
>  --
>  Mariano Absatz - El Baby
>  el (dot) baby (AT) gmail (dot) com
>  el (punto) baby (ARROBA:@) gmail (punto) com
>
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>

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