Incoming Mult-part Messages

We’ve just had our first MIME multi-part request from an external user
since going live with the system. The e-mail sent to the CCs and
AdminCCs didn’t contain a message (just the constant bit from the
template at the top), which confused some people.

In the ticket’s web page, the history shows the plain text part and the
HTML part is shown as an attachment, as is the ‘Word’ document that was
also attached.

I’m having a little trouble working out what is supposed to happen.
I’ve searched ‘RTFM’ and the mailing lists for “attachments” (and
“attachements”!) and “multipart”, but am still a little confused:

1 Is the behaviour I experienced ‘normal’, that is what’s supposed to
happen? I fear that I may have been over-enthusiastic in pruning a
template somewhere and destroyed something vital, but I can’t think
of a way of examining the default templates without installing ‘RT’

2 From discussion last autumn, it looks like the purpose
NotifyWithAttachment was to allow uploading and mail attachments
with the web interface. But presumably it could be used so that
attachments on incoming mail are distributed to CCs and AdminCCs?

However, in this case that would also have spammed everybody with
the 'Word' document.  That's probably acceptable, but not ideal if
there's a way of getting just the message without the attachment.

Thanks in advance for any light anybody can shed on this.