#!/bin/sh
# maildelayline - a script to resend emails at arbitrary times
# Copyright © 2007 MJ Ray - see end for zlib-like terms
#
# Make sure you can catch bounces from the resent emails
# - probably you should add a -f flag to the sendmail call.
#
# Also, keep your delayline incoming address secure somehow, else you'll spam

outdir=/home/mjr/outbox
sendmail="/usr/sbin/sendmail"

# Capture the email to a temporary file
mailfile=$(mktemp $outdir/incoming.XXXXXXXXXX)
cat - >$mailfile

# Extract the desired sending time
senddate="$(grep -m 1 '^X-Send-At: ' $mailfile | cut -f2- -d:)"

# Build mail to send: extract relevant headers and pseudo-headers
outmail=$(mktemp $outdir/mail.XXXXXXXXXX)
sed -n -e '/^\(message-id:\|in-reply-to:\|subject:\|references:\|from:\|sender:\|reply-to:\|content-\)/I,/^[^ 	]/{;/^\(message-id:\|in-reply-to:\|subject:\|references:\|from:\|sender:\|reply-to:\|content-\|[ 	]\)/Ip;};/^$/q' $mailfile >$outmail
sed -n -e '/^X-Send-At: /,/^$/{;/^X-Send-At: /!p;/^$/q;}' $mailfile >>$outmail

# Build mail to send: extract cleaned email body
sed -e '1,/^$/d;/^X-Send-At: /,/^$/d' $mailfile >>$outmail

# Put the email into the at queue
echo $sendmail -t '<' $outmail '&&' rm $outmail $mailfile | at "$senddate" || rm $outmail $mailfile

exit 0

#  This software is provided 'as-is', without any express or implied
#  warranty.  In no event will the authors be held liable for any damages
#  arising from the use of this software.
#
#  Permission is granted to anyone to use this software for any purpose,
#  including commercial applications, and to alter it and redistribute it
#  freely, subject to the following restrictions:
#
#  1. The origin of this software must not be misrepresented; you must not
#     claim that you wrote the original software. If you use this software
#     in a product, an acknowledgment in the product documentation would be
#     appreciated but is not required.
#  2. Altered source versions must be plainly marked as such, and must not be
#     misrepresented as being the original software.
#  3. This notice may not be removed or altered from any source distribution.