From: elee9sf@Menudo.UH.EDU
Date: Fri, 4 Jun 93 21:06:13 PDT
To: cypherpunks@toad.com
Subject: INFO: .forward
Message-ID: <199306050406.AA21108@Menudo.UH.EDU>
MIME-Version: 1.0
Content-Type: text/plain



> Would someone explain how to do this.  I need an idiot's
> description.  I tried to get my mail to go through a filter
> once....twice actually.  Never did get it to work.

Well, I'll give it a shot.  Sendmail optionally reads a file in your
home directory named .forward, and follows the instructions there.
Typically, a .forward contains another address, in which case mail
sent gets forwards to the address in the .forward file.  For example,
my .forward file on tree.egr.uh.edu is

elee9sf@menudo.uh.edu

so any mail sent to barrus@tree.egr.uh.edu gets forwarded to
elee9sf@menudo.uh.edu.

A more interesting application is to forward your mail to a command
(pipe mail to a command).  In that case, the .forward file reads

"|/path/mycommand options"

and mail gets piped to mycommand for further processing.  For
instance, the vacation program works by piping incoming mail to
vacation, which both files and responds for you.  Also, the cypherpunk
remailers work by using a .forward file to pipe incoming mail to the
scripts which make up the remailer.  Yet another example is the slocal
program which is part of the mh mail system; incoming mail gets piped
to slocal, which in turn relies on a configuration file
(.maildelivery) which contains instructions for handling the mail.

My idea was to have all mail sent to barrus@tree.egr.uh.edu piped
through pgp and then mailed to elee9sf@menudo.uh.edu.  The rough idea
is to do this:

"|/path/pgp -fea barrus | mail elee9sf@menudo.uh.edu"

Here, incoming mail gets piped to 'pgp -fea barrus' which encrypts the
message with my public key, and the result is piped to 'mail
elee9sf@menudo.uh.edu' which then mails the encrypted result to me.
For various reasons I'm still exploring, this didn't work (even with
PGPPATH set, piping to a script, etc.  I've got more things to try to
see why it isn't working.) on the NeXT.

So, I tried to do this from the menudo.uh.edu side.  Using the slocal
program and the associated .maildelivery file, I have mail which comes
from barrus@tree.egr.uh.edu (remember my mail from tree is forwarded
to menudo) piped through 'pgp -fea barrus' and then the result is
piped into an mh command which stores the mail in a folder.

Of course, this isn't a substitute for end-to-end encryption.  Here,
mail travels all the way to me before getting encrypted, so if
somebody wanted to snoop me they could just stand between the sender
and my account and eavesdrop.  A better solution would be to have the
sender encrypt the message!  But as I mentioned I was trying to set
this up so that replies to a USENET posting got encrypted before
finally getting dropped on menudo.  An improvement would be for me to
get the encryption and remailing working on the NeXT, but again, this
is inferior to having the sender encrypt in the first place.

You mentioned trying to put your mail through a filter - were you
trying to use the filter command of elm?  Sometimes you have to watch
subtle things like file permissions (slocal will not use a
.maildelivery file that is group or other readable) or pathnames (try
putting the fill path names when you use commands).

/-----------------------------------\
| Karl L. Barrus                    |
| elee9sf@menudo.uh.edu             | <- preferred address
| barrus@tree.egr.uh.edu (NeXTMail) |
\-----------------------------------/