MIME message parts from backends (specifically IMAP)

[Steinar Bang <sb@metis.no>]

Would it be possible to change the backend interface, to allow access
to different parts of multipart messages?

The reason I'm asking this question, is IMAP, and the possibility to
utilize one of IMAP's features.  IMAP lets you access the parts of a
multipart message separately (ie. the IMAP server parses the MIME
message and allows you access to the different parts (UoW imapd
currently does this, I'm told)).

The advantage of this, is that you can decide to download the text
parts of a message, but leave that 8MB MPEG attachment on the server
until you're on a LAN.

I tried to make use of this, using IMAP with Communicator 4.  But it
turns out that this MUA does it's own MIME processing, and always
fetches the entire message to do so.

One way to make use of this feature, would be if there was an IMAP
compliant way to make the server replace body parts with standin body
parts that use the URL access type for message/external-body (as
defined in <URL:http://ds.internic.net/rfc/rfc2017.txt>) and put the
IMAP URL
     <URL:http://www.internic.net/internet-drafts/draft-newman-url-imap-10.txt>
for said message part there.

However:
  1. this would require IMAP servers to do this, and I don't think
     they do, or can be persuaded to do so using an IMAP compatible
     way 
  2. this doesn't do away with the need for an IMAP Gnus backend to be
     able to access a message part individually


- Steinar

PS. I can hear Rich gritting his teeth over this, already...:-)