On Mar 26, 2014, at 5:47 PM, Fred Baker (fred) <f...@cisco.com> wrote:
> > On Mar 25, 2014, at 8:31 PM, Cutler James R <james.cut...@consultant.com> > wrote: > >> 3. Arguing about IPv6 in the context of requirements upon SMTP connections >> is playing that uncomfortable game with one’s own combat boots. And not >> particularly productive. > > That is one of my two big take-aways from this conversation. The other is > that operators of SMTP MTAs should implement RDNS for them, which I thought > we already knew. It is in several industry recommendations cf for instance BCP at www.m3aawg.org > > To my knowledge, there are three impacts that IPv6 implementation makes on an > SMTP implementation. One is that the OS interface to get the address of the > next MUA or MTA needs to use getaddrinfo() instead of gethostbyname() (and > would do well to observe RFC 6555’s considerations). Another is that, whether > on an incoming or an outbound connection, when the application gets its own > address from the OS (binary or as a character string), it needs to allocate > more storage for the data structure. The third is that it needs to be able to > interpret user@2001:db8::1 as well as user@dns-name and user@192.0.2.1. > and user@2001:db8::1.25 with user@192.0.2.1:25. Who had the good idea to use : for IPv6 addresses while this is the separator for the port in IPv4? A few MTA are confused by it. > All things considered, that’s a pretty narrow change set. > > Everyone here, no doubt, is clueful enough to implement RDNS for their MTAs. > We know that there are people in the world that don’t implement it for IPv4. > Yet, here we are, using SMTP/IPv4 to discuss this, and I don’t hear anyone > saying that IPv4 isn’t ready for prime time as a result of the fact of some > operators not implementing RDNS. > There is some confusion between MX selection and address selection, I tried to document it, and resolve the ambiguities in http://datatracker.ietf.org/doc/draft-martin-smtp-target-host-selection-ipv4-IPv6/ (comments at apps-disc...@ietf.org) Remember 70 to 90% of email is spam, blacklists can drop as much as 75% of spam at connection time (an IPv6 blacklist has problems due to size and impact on DNS). If we mess up the transition of SMTP to IPv6, less than 1 out of 10 emails in your mailbox will be remotely interesting….
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