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RFC 1894 describes a message-delivery-status MIME message format which
is similar to what you are asking for. If it were encapsulated in a
PGPMIME signed message then you would have the authentication security
that you want. The RFC is more oriented towards the MTA rather than MUA
level, so it would indicate that the message had arrived in the user's
mailbox, but not whether he had read it. However the 1894 syntax could
be extended to cover that case as well.
Cool.
You might want to take a look at the following drafts:
An Extensible Message Format for Message Disposition Notifications
draft-ietf-receipt-mdn-05.txt
and
MIME-based Secure EDI
draft-ietf-ediint-as1-04.txt
Great. KISS is definitely the right principle for OpenPGP. If we can do
secure receipts without altering the format, all the better.
Ian >:)
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