scripts/dc-dlvr

#!/bin/sh
# Copyright (C) 2008-2021 all contributors <meta@public-inbox.org>
# License: GPL-3.0+ <http://www.gnu.org/licenses/gpl-3.0.txt>
# This is installed as /etc/dc-dcvr on my system
# to use with postfix main.cf: mailbox_command = /etc/dc-dlvr "$EXTENSION"
DELIVER=/usr/lib/dovecot/deliver
CLAMDSCAN=clamdscan

# change if your spamc/spamd listens elsewhere
spamc='spamc'

# allow plus addressing to train spam filters, $1 is the $EXTENSION
# which may be "trainspam" or "trainham".  Only allow spam training
# when $CLIENT_ADDRESS is empty (local client)
case $1,$CLIENT_ADDRESS in
trainspam,) exec $spamc -L spam > /dev/null 2>&1 ;;
trainham,) exec $spamc -L ham > /dev/null 2>&1 ;;
esac

TMPMSG=$(mktemp -t dc-dlvr.orig.$USER.XXXXXX || exit 1)
CDMSG=$(mktemp -t dc-dlvr.orig.$USER.XXXXXX || exit 1)
rm_list="$TMPMSG $CDMSG"

cat >$CDMSG
$CLAMDSCAN --quiet - <$CDMSG
if test $? -eq 1
then
	$DELIVER -m INBOX.spam <$CDMSG
	exec rm -f $rm_list
fi

# pre-filter, for infrequently read lists which do their own spam filtering:
if test -r ~/.dc-dlvr.pre
then
	set -e
	mv -f $CDMSG $TMPMSG
	DEFAULT_INBOX=$(. ~/.dc-dlvr.pre)
	case $DEFAULT_INBOX in
	'') exec rm -f $rm_list ;;
	INBOX) ;; # do nothing
	*)
		$DELIVER -m $DEFAULT_INBOX <$TMPMSG
		exec rm -f $rm_list
		;;
	esac
	PREMSG=$(mktemp -t dc-dlvr.orig.$USER.XXXXXX || exit 1)
	rm_list="$rm_list $PREMSG"
	set +e
	mv -f $TMPMSG $PREMSG
	$spamc -E <$PREMSG >$TMPMSG
else
	$spamc -E <$CDMSG >$TMPMSG
fi
err=$?

# normal delivery
set -e

case $err in
1) $DELIVER -m INBOX.spam <$TMPMSG ;;
*)
	# users may override normal delivery and have it go elsewhere
	if test -r ~/.dc-dlvr.rc
	then
		. ~/.dc-dlvr.rc
	else
		$DELIVER -m INBOX <$TMPMSG
	fi
	;;
esac

exec rm -f $rm_list