crop-swap-mail-list/cropswap-sendmail.sh

#!/bin/bash
set -euo pipefail
WD=$(mktemp -d)
cleanup (){
	rm -rf "${WD}"
}
trap cleanup EXIT

DELIVERED=false
SENDMAIL="/usr/sbin/sendmail"
if ((DEBUG != 0)); then
	SENDMAIL="$DEBUGMAIL"
fi

cat - > "${WD}/original"
subject="$(reformail -c -x "Subject:" < "${WD}/original")"
if [ "${subject/\[${SUBJECT}\]/}" == "${subject}" ]; then
	subject="[${SUBJECT}] ${subject## }"
fi
reformail \
	-X "Date:" \
	-X "MIME-Version:" \
	-I "Subject: ${subject}" \
	-X "Subject:" \
	-I "List-Id: $MAILGROUP" \
	-X "List-Id:" \
	-I "List-Unsubscribe: <mailto:$MAILGROUP?subject=[UNSUBSCRIBE]>" \
	-X "List-Unsubscribe:" \
	-I "List-Subscribe: <mailto:$MAILGROUP?subject=[SUBSCRIBE]>" \
	-X "List-Subscribe:" \
	-I "List-Post: <mailto:$MAILGROUP>" \
	-X "List-Post:" \
	-I "List-Unsubscribe-Post: List-Unsubscribe=One-Click" \
	-X "List-Unsubscribe-Post:" \
< "${WD}/original" > "${WD}/headers"

reformime -s1 -e < "${WD}/original" | makemime -c "$(reformail -c -x 'Content-Type:' < "${WD}/original")" - > "${WD}/body"
echo "NOTICE:======== <<<" | makemime -c "text/plain" - > "${WD}/banner"
makemime -m multipart/mixed "${WD}/banner" > "${WD}/new"
makemime -j "${WD}/new" "${WD}/body" | cat "${WD}/headers" - > "${WD}/mail.new"

mv "${WD}"/mail{.new,}

declare -A SUBSCRIBED
declare -a actions
update(){
	alias="${actions[$1-1]}"
	email="${2}"
	SUBSCRIBED["$email"]="$alias"
}

exec 4< "${SLIST}.txt"
flock 4
mapfile -t -c 2 -C update -u 4 actions
flock -u 4

for email in "${!SUBSCRIBED[@]}"; do
	if [ "${email,,}" == "${NOFORWARD,,}" ]; then
		continue
	fi
	if [ "$TO" != "" ] && [ "$email" != "$TO" ]; then
		continue
	fi
	echo "Forwarding mail: "
	echo "From: ${FROM} <${MAILGROUP}>"
	echo "To: ${SUBSCRIBED["$email"]} <${email}>"
	"$SENDMAIL" -F "${FROM}" -f "${MAILGROUP}" "${SUBSCRIBED["$email"]} <${email}>" < "${WD}/mail"
	DELIVERED=true
done
if ! $DELIVERED; then
	"$DEBUGMAIL" undelivered
	exit "$UNHANDLED"
fi