Re: [Extra] Is this a plausible IMAP extension ?

[Arnt Gulbrandsen <[e-mail]>]

On Thursday 28 February 2019 17:12:13 CET, John Levine wrote:
> Urrgh.  Most of the mail that's likely to have a logo is 
> multipart/alternative
> and I'm not interested in wrapping contents in yet more MIME 
> layers, which would
> among other things break any existing DKIM signatures.

You don't need that. Look at 3676. It doesn't wrap, it marks. In this case, 
either mark the top-level multipart with the content-id of the logo

  content-type: multipart/mixed; boundary=foo; logo=bar

(the logo will mostly have a content-id because the html refers to it) or 
mark the bodypart with the logo

  content-type: image/jpeg; content-id=bar; logo

or mark the logo's disposition

  content-disposition: attachment; logo

It's not obvious to me which way is the best. Is being a logo part of the 
type or rather part of the disposition? I don't even want o discuss that.

All are immutable though, since they're part of the message, and the info 
is returned as part of the FETCH BODYSTRUCTURE command most/all clients 
use. Very easy to implement in typical clients, and zero work for the 
server.

Arnt