Re: IPv6 isn't SMTP

[James R Cutler <james.cutler () consultant com>]

On Mar 26, 2014, at 8:47 PM, Fred Baker (fred) <fred () cisco com> wrote:

> On Mar 25, 2014, at 8:31 PM, Cutler James R <james.cutler () 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.
>
> 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. 
>
> 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.
>
> ...

Fred Baker describes the requirements in a most satisfactory manner.

Thank you, Fred.

James R. Cutler
James.cutler () consultant com
PGP keys at http://pgp.mit.edu

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