I have just submitted an Internet Draft entitled
MIME Content-Type for Delivery Status Notifications
which describes a well-defined format for delivery reports,
and non-delivery reports. (there is also a draft describing
an SMTP extension to request such reports). For the time being,
these can also be had via anonymous ftp to cs.utk.edu,
directory pub/moore, files:
draft-moore-mime-delivery-00.txt (mime content-type)
draft-moore-smtp-drpt-00.txt (smtp extension)
(note that the Internet Drafts people may assign different
filenames.)
Keith Moore