I'm a little confused as to why this issue isn't considered more
critical within the MIME community. Successfully transmitting the name
of an attachment and correctly noting whether some textual information
is to be treated as an attachment or as part of the message body is
also very important. We have some pretty bad failure modes when this
information is not correctly transmitted.
like several other PC-based mail clients, we use a specially-named
attachment to pass custom rich text, custom attributes and forms
information. When this name isn't preserved, the MIME-based Unix
version can't recognize this information. (Note that we're trying to
get this through gateways, so we're not simply talking MIME to MIME
mailer here and that limits the strategies we can take).
Also, by default the client will send the text body as both plain text
and within this special attachment (along with the formatting info).
When our client receives the message, it assumes the text of the
message is completely specified in the attachment and discards the
actual body. If a gateway has inserted the attachment into the body,
the attachment is completely lost (I won't go into details about why
this makes sense). Bottom line is the Content-Disposition becomes a
pretty important piece of information.