OpenDKIM

To enable openDKIM signing your outgoing eMails using debian:

In the new directory /etc/opendkim/keys/example.com you create a new key pair:

opendkim-genkey -r -h rsa-sha256 -d example.com -s mail

The resulting mail.txt file contains the lines you have to add to your DNS. You might have to change the user/group of mail.private to opendkim:opendkim.

Then add a new line to /etc/opendkim/KeyTable containing:

mail._domainkey.example.com example.com:mail:/etc/opendkim/keys/example.com/mail.private

And add to SigningTable this line

*@example.com mail._domainkey.example.com

And reload the opendkim service.