Re: [ietf-smtp] Curious, with this now being associated to emailcore, should list name change?

John C Klensin <> Wed, 22 July 2020 01:08 UTC

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Date: Tue, 21 Jul 2020 21:08:43 -0400
From: John C Klensin <>
To: Keith Moore <>,
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Subject: Re: [ietf-smtp] Curious, with this now being associated to emailcore, should list name change?
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--On Tuesday, 21 July, 2020 20:48 -0400 Keith Moore
<> wrote:

> On 7/21/20 6:01 PM, John C Klensin wrote:
>> Pete, I think the core issue is the amount of trash we are
>> accumulating and passing around.  I don't see that as a
>> 5322bis problem.
> I think it's slightly deeper than that, which is that every
> time one party adds a new header field, some number of other
> parties decide that they can delete or modify that field, or
> use it to validate or invalidate the message.   So random
> parties making random decisions about message headers are
> detrimental to email reliability.

I agree with that.  But that is the justification for registered
header field names, preferably well-documented and stable ones.

I contend that:

X-I-know-what-this-means-and-I-am-not-going-to-tell-you: (Longer-
   than 35 characters but much shorter than 78)

does no one (other than maybe me) any good (with or without the
"X-".  If there are sufficiently many like that, they are
invitations to exactly the behavior to which you object.

I think this is probably a bad idea (or just short of nightmare)
but I wonder whether if we created a registration tree for
headers named
     private.* :
required registration of whatever came next, and then declared
open season on the rest if that would make things better.  Or


Noting (to my surprise, I had forgotten) that section 3.6.8 of
RFC5322 allows any printable ASCII character other than SP or
colon in field names.

As I said, probably a bad idea, but the idea that these things
were all going to be registered and documented has obviously