Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!wuarchive!psuvax1!hsdndev!cmcl2!kramden.acf.nyu.edu!brnstnd
From: brnstnd@kramden.acf.nyu.edu (Dan Bernstein)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Certified SMTP mail
Message-ID: <27915:Feb1200:07:5191@kramden.acf.nyu.edu>
Date: 12 Feb 91 00:07:51 GMT
References: <C13C5DEE293FE00507@ROSEVC.Rose-Hulman.Edu> <1991Feb11.164855.22742@zoo.toronto.edu> <122372@uunet.UU.NET>
Organization: IR
Lines: 11

There is a different kind of mail system where return receipts are
perfectly natural. All messages are very short, but can be accompanied
by one or more files that aren't sent at first but are held on the
sender's system. The recipient of the message can retrieve the
files---possibly compressed, encrypted, checksummed, whatever---with a
command or two. (When the initial message isn't required, this turns
into a BITNET-style file transfer system.) The sender is told when the
files are picked up, so he can use them as a (voluntary) return-receipt
system.

---Dan