dccifd / greylisting problems
el.baby at GMAIL.COM
Tue Aug 3 16:08:25 IST 2004
On Mon, 2 Aug 2004 10:46:57 -0500, Smart,Dan <smartd at vmcmail.com> wrote:
> 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.
> > -----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
-------------------------- MailScanner list ----------------------
To leave, send leave mailscanner to jiscmail at jiscmail.ac.uk
Before posting, please see the Most Asked Questions at
http://www.mailscanner.biz/maq/ and the archives at
More information about the MailScanner