Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!sdd.hp.com!ucsd!ucbvax!NADA.KTH.SE!maguire
From: maguire@NADA.KTH.SE (Gerald Maguire)
Newsgroups: comp.mail.multi-media
Subject: Multi-media mail standards; Forw: Use of ODA in the Internet
Message-ID: <9008142236.AA18311@nada.kth.se>
Date: 14 Aug 90 22:36:07 GMT
References: <Yam3pNS0M2YtM1ArRd@thumper.bellcore.com>
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: inet
Organization: The Internet
Lines: 14

There was a mail system built on LISP at HP Labs which allowed you to
send S-exprs and have them executed by the receiver. As a security
feature you could set a flag that you did NOT want the s-exprs to be
automatically executed but could eval them manually. It is quite
straight forward to make this conditional on the sender. However, if
you want programmability there is no free lunch. You could evaluate
the experessions inside an environment where you redefined functions
which could change the state of the system as "safe" operators - which
could trap to a handler, rather than perform the operation (for
example "rm" and write operations). This is one major advantage to
execution within an environment which does name lookups using the top
most directory (which means you could do the same for PostScript).

Chip