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 192.25.206.10 debian.org MX master.debian.org master.debian.org A 70.103.162.30 [~]$ telnet 192.25.206.10 25 Trying 192.25.206.10... Connected to 192.25.206.10. Escape character is '^]'. 220 gluck.debian.org ESMTP Exim 4.50 Mon, 10 Jul 2006 18:06:29 -0600 helo utumno.angband.pl 250 gluck.debian.org Hello acrc58.neoplus.adsl.tpnet.pl [83.11.4.58] mail from: [EMAIL PROTECTED] 250 OK rcpt to: [EMAIL PROTECTED] 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. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]