#!/usr/bin/zsh --
# Program that delays mail files, to catch bulk-spam before it is send.
# This script imports mail-files into the antiSPAM-delay-spool directory.
#
# Program released under the terms of the GNU GPL3.
# This is free software. You are free to copy and redistribute.
# No warranty. See http://www.gnu.org for license details.
# (C) 2007 Jos Boersema
#
# Usage: prog MAIL_FILE [exim4in|headers|RECIPIENTS]
# Manual:
#        Configure user-variables
#            -> mkdir a spool-directory for spam-delay,
#               point SPAM_DELAY_SPOOL (below) to it
#        Decide how to get to the number of recipients and sender
#            -> if you supply the mails in headers/body format, call
#               with argument "headers"
#               Note:   When users can set the From: field freely, and
#                       you use that to determine user, the system has
#                       an obvious spammer hole.
#            -> if you supply the mails in exim4 spool format, call
#               with argument "exim4in" <test first>
#            -> if you know the amount of recipients, put that number
#               in the environment under MAILDLAY_AMOUNT, and put
#               the name/e-mail-address of the sender in MAILDLAY_NAME
#        Test: copy a mail-file to /tmp/whatever, run the program to
#              verify it gets into the spam-delay. It should have a name:
#              SENDER-NUMBER_OF_RECIPIENTS-ORIG_NAME, example:
#              joshb@xs4all.nl_2__1IKwyz-0000vW-1D-D
#        Operation: running program passes mail-file into antiSPAM-delay-spool
#

########################################################################
#######             USER VARIABLES                          ############
########################################################################

# Set this to a directory that acts as a temporary bulk-spam delay buffer.
#SPAM_DELAY_SPOOL="/var/spool/mail/antispamdelay"
SPAM_DELAY_SPOOL="/tmp/antispamdelay"

########################################################################
#######                  END                                ############
########################################################################

MAIL_FILE="${1}" #The file containing the mail.
RECIPIENT_METHOD="${2}" #The method of computing the # of recipients,
                        #Methods: "env", "headers", "exim4in"

if test "headers" = "${RECIPIENT_METHOD}"
	then
    # Count how many recipients, based on To:/Cc:/Bcc: headers ...
		# Only greps through headers.
		RECN=$( echo '1,/^$/p' | ed -s "${MAIL_FILE}" | grep -E '^To:.*@|^Cc:.*@|^Bcc:.*@' | sed -e 's/@/@\n/g;' | grep -E '@' | wc -l )
		# Get e-mail address in From: header
		# Only greps through headers.
		FROMUSER=$( echo '1,/^$/p' | ed -s "${MAIL_FILE}" | grep -E '^From: ' | sed -e 's/From: //;s/[, ][^@]*$//;s/.* [<]*//;s/[^a-zA-Z0-9]*$//;' ) 
elif test "exim4in" = "${RECIPIENT_METHOD}"
	then
		# Count how many recipients, based on what exim4 seems to store in its spool
		# This is based on guessing from looking at the format ...
		# ... gets the first single-number in the file.
		RECN=$( echo '/^[0-9]*$/p' | ed -s "${MAIL_FILE}" )
		FROMUSER=$( echo '/@/p' | ed -s "${MAIL_FILE}" | sed -e 's/[<]*//;s/[^a-zA-Z0-9]*$//;' ) 
elif test "env" = "${RECIPIENT_METHOD}"
	then
		RECN="${MAILDLAY_AMOUNT}" #expected in environment...
		if test -z "${RECN}"
			then
				echo "maildlay: expected number of recipients in \${MAILDLAY_AMOUNT} in the environment, not found."
				echo "maildlay: aborting ..."
				#ERROR-EXIT
				false
				exit
		fi
		FROMUSER="${MAILDLAY_NAME}" # <same>
		if test -z "${FROMUSER}"
			then
				echo "maildlay: expected sender in \${MAILDLAY_NAME} in the environment, not found."
				echo "maildlay: aborting ..."
				#ERROR-EXIT
				false
				exit
		fi
else
		#USAGE	
		echo "maildlay: usage error, specify a method for retreiving sender and amount of recipients [headers|exim4in|env], aborting."
		#ERROR-EXIT
		false
		exit
fi

#Move the mail-file into the spam-delay-spool
#The name indicates user + number-of-recipients + original filename.
mv "${MAIL_FILE}" "${SPAM_DELAY_SPOOL}/${FROMUSER}_${RECN}__${MAIL_FILE:t}"