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Pete Resnick | 10 Jul 1998 19:56

Re: 8BITMIME to 7BIT

A discussion started over on the international mail list, but the question
I had seemed more appropriate for ietf-smtp and ietf-822. I've Bcc'ed the
international mail list.

On 7/8/98 at 7:21 PM -0700, Ned Freed wrote:

>You have to check for and make sure not to change anything within a
>multipart/signed. (Multipart/encrypted is a nonissue, as the entire part is
>encoded.) If the multipart/signed contains 8bit I currently default to sending
>it through untouched, which of course is technically illegal but works often
>enough that it rarely results in a problem. I also support configurations
>where
>the signature is simply removed in such cases, either with or without an
>attempt to verify.
>...
>Note, however, that the contents of multipart/signed are supposed to be
>7bit-friendly when multipart/signed is used with potentially 7bit-only
>transports like SMTP. Unfortunately clients exist that botch this.

So I was thinking: Would it be reasonable for us to create a field for the
signature sort of like:

        Content-Signed-Part-Encoding: 8bit

which would indicate the CTE used to compute the signature? That way, if an
MTA does downgrade a message, the signature can still be verified because
you can always recover the original content after a downgrade.

The rule for gateways would be: When downgrading a multipart/signed which
already has a Content-Signed-Part-Encoding, preserve that field exactly as
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Ned Freed | 10 Jul 1998 23:41

Re: 8BITMIME to 7BIT

> > Note, however, that the contents of multipart/signed are supposed to be
> > 7bit-friendly when multipart/signed is used with potentially 7bit-only
> > transports like SMTP. Unfortunately clients exist that botch this.

> So I was thinking: Would it be reasonable for us to create a field for the
> signature sort of like:

>         Content-Signed-Part-Encoding: 8bit

> which would indicate the CTE used to compute the signature? That way, if an
> MTA does downgrade a message, the signature can still be verified because
> you can always recover the original content after a downgrade.

I don't think this has much chance. Deploying such a field would certainly be a
nightmare, as it requires new support in things generating signatures, checking
signatures, and doing MIME downgrades.

Changing signature generators is the easiest thing: Just generate the new
field. (It has to have exactly the same value as the CTE field, but that's
easy.) But if you're going to make a change in signature generation, why not
simply change things generating signatures to generate 7bit material?

Systems doing downgrading have a bigger problem. They have to:

(1) Check and make sure this field is present on every 8bit part.
(2) Check and make sure a corresponding CTE field is also present with
    identical content, down to the letter.
(3) Encode the part.
(4) Change the value of the CTE to base64 or quoted-printable, but making
    sure not to change the positioning of any of the fields and making sure
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Ian Bell | 17 Jul 1998 16:25

Re: draft-gellens-format-00

On Fri, 14 Aug 1998, Randall Gellens <randy <at> qualcomm.com> writes
>At 7:32 AM -0700 8/14/98, Ian Bell wrote:
>

>>If there is no way to tag a line as "don't wrap this", replies to
>>standard text/plain messages MUST NOT be promoted to format=flowed
>
>Promotion to format=flowed should be done with care, and probably only
>under user direction, as I see it.  It's the safest course.
>

Users won't be aware of the problems of promoting to format-flowed -
they will probably always do it so that their own text will look pretty.
The result will be that quoted text will get miss-attributed whenever
any non-standard quote character has been used.

>>Comments were solicited as to the UseNet signature convention. 
>
>Many people generate it, but does anyone care about it on reception?
>

Yes! It seems to me that the major purpose of using a standard sig-
separator is that receiving MUAs can strip off the signature when
replies are being prepared. This prevents messages being bloated by
including quoted signatures, or forcing users to snip out signatures by
hand. Not treating "-- " specially may break this.

Overall, I tend to agree with the original consensus that the use of
trailing space is not a good solution to the problem of paragraph-
oriented text. Indeed, most solutions appear to be worse than the
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