Create a DKIM keypair

mk_dkimpair.sh

#!/bin/bash

set -e

if [ $# -eq 0 ]; then
        echo "Use: $0 <domain name>"
        exit 1
fi

DOMAIN=$1

openssl genrsa -out dkim/$DOMAIN-private.pem 1024 -outform PEM
openssl rsa -in dkim/$DOMAIN-private.pem -out dkim/$DOMAIN.pem -pubout -outform PEM

chown -R Debian-exim:Debian-exim /etc/exim4/dkim
chmod 640 /etc/exim4/dkim/*
chmod 750 /etc/exim4/dkim

PUBLICKEY=`sudo cat dkim/$DOMAIN.pem | tail -n +2 | head -n -1 | tr -d '\n'`;

echo "DKIM key pair created for $DOMAIN"
echo
echo "Cut and paste the following into your TXT DNS record:"
echo "k=rsa; p=$PUBLICKEY"