On Fri, Jul 17, 2009 at 11:37:50AM -0500, David Champion wrote: > * On 17 Jul 2009, lee wrote: > > > > Well, I'm not trying to mislead someone. Where is defined what an > > attachment is for the context of a MUA, and who made the definition? > > Content-Disposition's role is described in RFC 2183. But "attachment" > is a very ambiguous term.
They have a good way of putting it in RFC 2183: " Two common ways of presenting multipart electronic messages are as a main document with a list of separate attachments, and as a single document with the various parts expanded (displayed) inline. The display of an attachment is generally construed to require positive action on the part of the recipient, while inline message components are displayed automatically when the message is viewed. A mechanism is needed to allow the sender to transmit this sort of presentational information to the recipient; the Content-Disposition header provides this mechanism, allowing each component of a message to be tagged with an indication of its desired presentation semantics. " There is a distinction between attachments and other message components. You could say everything not designated to be displayed automatically in line is considered as an attachment. > It's less about what the user wants to do, and more about the > component's relationship to the message that the sender composed. But > this is still rather subjective. There could be a counter counting message components. The RFC 2183 is supposed to define a means *for the sender* to specify how he wants parts of the message to be displayed. How the recipient deals with the message is up to him. Is there an RFC that defines how a MUA is supposed to deal with such multipart messages? RFC 2183 seems to (reasonably) say only a minimum about what MUAs should do.
