Generate DKIM key pair and entry for in your bind zones.

gen-dkim-key.sh

#!/bin/sh

DOMAIN=$1
SELECTOR=${2:-mail}

if [ -z "$DOMAIN" ]; then
	echo "Usage: $0 domain"
	exit 1;
fi

openssl genrsa -out dkim-${DOMAIN}.key 2048
openssl rsa -in dkim-${DOMAIN}.key -out dkim-${DOMAIN}.pub -pubout -outform PEM

DNS=`cat dkim-${DOMAIN}.pub | grep -v "-"`

echo "Add the following record to your DNS zone."
echo "##########################################"
echo ""
echo "${SELECTOR}._domainkey	IN	TXT	( \"v=DKIM1; t=y; k=rsa; p=\""
for line in $DNS; do
	echo "\t\"${line}\""
done
echo ")"