Re: The issue of mime parsing

Rickard:
[Workflow A]
>>   1. Notification (using something like your field structure).
>>   2. Receivers MUA parses the notification including the
>>      "external-body-only MIME" data (the manifest).
>>   3. Receivers MUA fetches any body parts it wants and displays them.
>>
[Workflow B]
>>   1. Notification (using some really simple field structure).
>>   2. Recivers MUA parses the notification and fetches
>>      a message that uses your message field structure.
>>   3. Recivers MUA parses the message, including any generic MIME
>>      in the body part and displays the content.
>>   4. If the sender has chosen to include some parts as
>>      MIME/external-body the receivers MUA may also download
>>      and display them.

Stefan Karrmann:
> How does [Workflow A] knows who has fetched a body part? You need
> this information to know the delivery status of the message.

This is a good point. I agree that the sending side should keep track
of the delivery status of outgoing messages to know when they can be
deleted. But isn't this problem also present for external/body
messages in Workflow B? : Once the receiver has downloaded the
message in 'point 2', exactly for how long should the external-body
servers keep the message parts available?

That said, I think it is possible even within ordinary HTTPS to keep
track of delivery status. Either by automatic parsing of the log
files from the web server, or by replacing the idea of using
something like:
  https://example.com/im2k/8A932r89/mybody.txt
with something more like:
  https://example.com/cgi/im2k.cgi?msgid=8A932r89&part=mybody.txt
I.e,: a message is fetched by running a cgi-script on the server
that besides giving out a message part, also carefully keeps track of
its delivery status.

> If you use a different external-body for each receiver the
> 'external-body' server have to tell im2k who has fetched the
> message.

Now, instead of having 'external-body' servers "telling" the outgoing
im2k server every time a message has been downloaded, I suggest that
their role is only to serve parts and keep track of downloads.
Instead we let the outgoing im2k server iterate over each email and
fetch delivery status data from the 'external-body servers' to decide
if that message's "delivery finished" criteria is fullfilled.

//Rickard