-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 8 May 2008 at 18:50, Tony Finch <[EMAIL PROTECTED]> said:
> On Thu, 8 May 2008, Robert A. Rosenberg wrote: > > OTOH, if/when the highest priority is ONLY CNAMEs (even if lower/back-up > > MXs are A/AAAA which you can support) do an immediate reject since the > > back-up MXs will never be able to deliver to the primary servers (due to > > their being invalidly defined as CNAMEs). > > That's not necessarily true: (1) Backup MXs don't have to use the standard > routing algorithm to deliver email. (2) If the verifying MTA is IPv4-only, > the primary MX is IPv6-only, and the backup MX is dual-protocol, your > proposed algorithm will falsely bounce the message. The backup MXs you didn't plan on sending mail to may, furthermore, not mind CNAMEs, even if you do. From the implementation point of view, CNAMEs can be highly transparent. To make this algorithm work, you have to intentionally look for an error condition at the primary. You would no longer be seeking a next hop within your IPvX capabilities only using the standardised search. I think that's outside my scope for a clean implementation, but others may feel differently. Cheers, Sabahattin - -- Sabahattin Gucukoglu <mail<at>sabahattin<dash>gucukoglu<dot>com> Address harvesters, snag this: [EMAIL PROTECTED] Phone: +44 20 88008915 Mobile: +44 7986 053399 http://sabahattin-gucukoglu.com/ -----BEGIN PGP SIGNATURE----- Version: PGP 8 Comment: QDPGP - http://community.wow.net/grt/qdpgp.html iQA/AwUBSCNVLCNEOmEWtR2TEQIm4gCg7wLCn9G8u2AhiR1k9Wpqz1j6Q28Anibd HR9X3joDoUUaggBOXdNpC9jS =IELg -----END PGP SIGNATURE-----
