[Python-Dev] Completing the email6 API changes.
R. David Murray
rdmurray at bitdance.com
Mon Sep 2 23:40:55 CEST 2013
On Mon, 02 Sep 2013 16:06:53 +0900, "Stephen J. Turnbull" <stephen at xemacs.org> wrote:
> >>>>> Glenn writes:
> > >>>>> Steve writes:
>
> >> OTOH, if the message is structured
> >>
> >> multipart/related
> >> multipart/alternative
> >> text/plain
> >> text/html
> >> image/png
> >> image/png
> >>
> >> the receiver can infer that the images are related to both text/*
> >> parts and DTRT for each.
>
> >With the images being treated as attachments. Or is there a syntax to
> >allow the text/html to embed the images and the text/plain to see them
> >as attachments?
>
> I believe the above is that syntax. But the standard doesn't say
> anything about this. The standard for multipart/alternative is RFC
> 2046, which doesn't know about multipart/related. RFC 2387 doesn't
> update RFC 2046, so it doesn't say anything about
> multipart/alternative within multipart/related, either.
>
> >I think the text/html wants to refer to things within its containing
> >multipart/related, but am not sure if that allows the intervening
> >multipart/alternative.
>
> I don't see why not. But it would depend on the implementations,
> which we'll have to test before recommending the structure I
> (theoretically :-) prefer.e
I'm still not understanding how the text/plain part *refers* to the
related parts. I can understand the structure Glen found in Applemail:
a series of text/plain parts interspersed with image/jpg, with all parts
after the first being marked 'Contentent-Disposition: inline'. Any MUA
that can display text and images *ought* to handle that correctly and
produce the expected result. But that isn't what your structure above
would produce. If you did:
multipart/related
multipart/alternative
text/html
text/plain
image/png
text/plain
image/png
text/plain
and only referred to the png parts in the text/html part and marked all
the parts as 'inline' (even though that is irrelevant in the text/html
related case), an MUA that *knew* about this technique *could* display it
"correctly", but an MUA that is just following the standards most
likely won't.
I don't see any way short of duplicating the image parts to make it
likely that a typical MUA would display images for both a text/plain
sequence and a text/html related part. On the other hand, my experience
with MUAs is actually quite limited :)
Unless there is some standard for referring to related parts in a
text/plain part? I'm not aware of any, but you have much more experience
with this stuff than I do. (Even text/enriched (RFC 1896) doesn't seem
to have one, though of course there could be "extensions" that
define both that and the font support you used as an example.)
--David
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