Re: greylisting on debian.org?
On Mon, Jul 10, 2006 at 05:57:45PM +0200, Adrian von Bidder wrote:
> On Monday 10 July 2006 02:17, Matthew R. Dempsky wrote:
> > On Sun, Jul 09, 2006 at 05:02:39PM -0700, Thomas Bushnell BSG wrote:
> > > Another problem is with hosts that do not accept a message from an MTA
> > > unless that MTA is willing to accept replies. This is a common spam
> > > prevention measure.
> > It also prevents mail from setups that use different servers for inbound
> > and outbound mail.
> Hmm. I've not seen this kind of sender verification. As I know it, the
> receiving MX connects the regular MX for the sender address to see if
> *that* is ready to receive mail. Works beautifully if outbound != inbound.
In fact, broken servers which don't obey MX will _already_ fail:
debian.org A 22.214.171.124
debian.org MX master.debian.org
master.debian.org A 126.96.36.199
[~]$ telnet 188.8.131.52 25
Connected to 184.108.40.206.
Escape character is '^]'.
220 gluck.debian.org ESMTP Exim 4.50 Mon, 10 Jul 2006 18:06:29 -0600
250 gluck.debian.org Hello acrc58.neoplus.adsl.tpnet.pl [220.127.116.11]
mail from: firstname.lastname@example.org
rcpt to: email@example.com
550 relay not permitted
MX records have been with us for 20 years, so I don't think a
legitimate mailer can ever disobey one. Of course, illegitimate
mailers often do.
1KB // Microsoft corollary to Hanlon's razor:
// Never attribute to stupidity what can be
// adequately explained by malice.