On Wed, May 10, 2006 at 02:48:42PM -0400, Kevin A. McGrail wrote: > Further, I believe there really is a "standard' to publish a blank MX record > at priority 0 but I think I heard about it from Jan-Pieter Cornet. Anyone > know if this has a real RFC or anything?
It was described in a now-expired ietf document draft-delany-nullmx-00.txt, still available at: http://ietfreport.isoc.org/all-ids/draft-delany-nullmx-00.txt It works even for clients that do not recognise the protocol, because "." has no A/AAAA records associated with it, so it cannot be used to deliver email to it. However, (and I just found that out by googling for the exact reference), it is a bad idea because of largely uncachable, unnecessary lookups to the root nameservers, as explained in email threads here: http://www.mhonarc.org/archive/html/ietf-mailsig/2005-04/msg00015.html and here: http://www.ops.ietf.org/lists/namedroppers/namedroppers.2005/msg00939.html As far as I know, there is no newer standard to mark a domain as not used for email (maybe SPF -all). But since we implemented it anyway, I do log such rejections, where the _sending_ domain is marked as not-for-email using MX 0 . We rejected almost 0.09% of the emails using this method yesterday (6695 out of 7452398 mails). 5951 rejects were for angelfire.com, 75 for altavista.se, and then there are 43 other domains with fewer rejections. Of those 43, 13 domains had "yahoo" in the name, totalling 152 rejected emails (Mark Delany, who initially proposed this, works at yahoo). -- Jan-Pieter Cornet <[EMAIL PROTECTED]> !! Disc lamer: The addressee of this email is not the intended recipient. !! !! This is only a test of the echelon and data retention systems. Please !! !! archive this message indefinitely to allow verification of the logs. !! _______________________________________________ NOTE: If there is a disclaimer or other legal boilerplate in the above message, it is NULL AND VOID. You may ignore it. Visit http://www.mimedefang.org and http://www.roaringpenguin.com MIMEDefang mailing list [email protected] http://lists.roaringpenguin.com/mailman/listinfo/mimedefang
