This is a small shell script that runs the commands necessary to enable DKIM for outgoing emails on a standard exim4 installation on Debian/Ubuntu and the like. For other distributions, some tweaks are probably necessary. After running the script, you will have to add a TXT DNS record for the domain: The script will tell you what record to add, too. If you have a more complex setup, with many domains and the like, it's somewhat more complicated, and you'll probably have to read up on DKIM for real, even though it's boring.