comast email issues, who else has them?

william(at) william at
Mon Sep 11 19:35:24 UTC 2006

On Mon, 11 Sep 2006, Tony Finch wrote:

> On Mon, 11 Sep 2006, william(at) wrote:
>> On Mon, 11 Sep 2006, Tony Finch wrote:
>>> Far better to use a Received: header stating HTTP in the "with"
>>> protocol field. (And the IANA registry should be updated to include
>>> that as one of the standard values.)
>> That suggestion is likely to be contrary to SMTP design. Received trace
>> fields are for use of recording of where data that was RFC2822 formatted
>> came from and how. Use of these fields also assumes that start of email
>> transmission took place somewhere else.
> I'm not entirely convinced by that argument. You could squint a bit
> and view webmail as a sort of gatewaying, in which case it makes sense to
> map webby concepts onto 821 and 822 as accurately as possible.

You need to have protocol to map it from. HTTP is not a protocol but 
type of transport of initial email submission data to a submission

> The other
> reason for using Received: for this kind of job is it scales better to
> other submission methods: what about an XMPP-to-email gateway, for
> example? It would be madness to define ad-hoc X- headers for each
> submission protocol.

I never said about defining X- fields for each protocol (although it
does appear to be the way things are being done right now). I said
that there is a need for submission trace field to identify source of
submission no matter how initial submission of data was done.

As far as XMPP if you can define proper mapping from and to SMTP then
you likely can start using "with" clause in Received for when first
SMTP email server is talking about message that came from XMPP.

>> The "with" clause in Received is used to indicate the "transport"
>> protocol but assumes that data itself is already properly formatted
>> (compare to that the same type of L7 protocol can use either TCP or UDP;
>> this is not perfect fit but gives you some idea).
> What about "with MMS" where the message format is not (quite) 822?

They defined proper mapping in RFC4356. Personally I think mapped protocols
should use "via" clause but it appears the way things are currently being 
done is that when mapping exist then "with" can be used. If you do not
have mapping and just using protocol for direct transfer of data then
"with" is only appropriate if entire data was already in appropriate 
RFC2822 form.

>> If you really want to indicate the source of transmission for non-SMTP
>> origination point, the best is to create new trace field for this purpose.
>> With Received the closest clause would be "via" but I think via is largely for
>> use with complete message being gatewayed through non-SMTP protocol and this
>> is probably not the correct use of it either.
> The only non-TCP via defined at the moment is UUCP, which I guess implies
> batch SMTP - i.e. "via" is the level under the message transport protocol.

I think that "via" is probably for use with a transport-level protocol 
independent of internet, i.e. gateway to/from non-internet world. That is 
why I think that "via" would have been better for use with "MMS". In any
case I've yet to see any convincing argument that "with HTTP" as couple
places are doing is appropriate nor is "via HTTP" likely any better.

P.S. I've distinct feeling there < 1% on this list who care about such
details of SMTP as we discussed and are interested in discussing it (the 
person who raised the issue originally probably only meant that he wants
to see ip address of the user creating webmail message and does not care 
how that information is carried as long as all are doing it). For protocol
details, perhaps it would be better if this discussion were to move to 
ietf-smtp at

William Leibzon
Elan Networks
william at

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