#!/bin/sh
#
# localpostproc - A sample postproc which changes the submission email server
#		  based on user-supplied criteria.
#
# The basic concept is that we change where we submit mail to based on the
# message contents.  We use scan(1) to get out fields we care about.  But
# really, you could use ANY criteria, such as environment variables,
# recipients, etc etc.
#

#
# Find the draft message, always the last argument, and whether we've
# been called with -whom;  the latter sucks.
#
# The case statement has to know about switches that take arguments;
# add to this list as necessary.
#

whom=0

find_draftmessage() {
	while test $# -gt 0; do
		case "$1" in
		-al* | -filt* | -wi* | -client | -idanno | -server | \
		-partno | -saslmech | -user | -por* | -width | \
		-file* | -mhl* | -mt* | -cr* | -lib* | -auth* | -sendmail)
			shift
			;;
		-whom)
			whom=1
			;;
		-*)	;;
		*)	
			draftmessage="$1"
			return 0
			;;
		esac
		shift
	done

	echo "Cannot find draft message name in argument list"
	exit 1
}

realpost="$(mhparam libdir)/post"

if [ $# -eq 0 ]; then
	echo "Usage: [post switches] filename"
	exit 1
fi

find_draftmessage "$@"

if [ $whom -eq 1 ]; then
	exec "$realpost" "$@"
fi

fromhost=$(scan -format '%<{resent-from}%(host{resent-from})%|%(host{from})%>' -file "$draftmessage")

if [ $? -ne 0 ]; then
	echo "Unable to run scan on draft file $draftmessage, aborting"
	exit 1
fi

if [ -z "$fromhost" ]; then
	echo "Could not determine hostname of From: address"
	exit 1;
fi

#
# Here we use the hostname in the "from" address, but you could use anything
#

case "$fromhost" in
	*host1.com)
	postflags="-server smtp.host1.com -sasl -port submission"
	;;

	host2.com)
	postflags="-server smtp.host2.com -sasl -tls -port submission"
	;;

	*)
	echo "Don't know how to send email from $fromhost"
	exit 1
	;;
esac

exec "$realpost" $postflags "$@"