The domain key, i.e. the domain key to the DNS record in, (is automatically created when you add a domain name in the control panel) key that serves, the fact that the email recipient can identify the sender. This prevents, false e-mail address from received email.
Check: http://dkimcore.org/tools/ and the control panel DNS zone copy the key so that shouldn't be in the ” ” symbol and copy and paste the http://dkimcore.org/tools/ website Check the dkim Core Key Record section.
You should see this after checking it: This is a valid DKIM key record
The domain keys cPanel and plesk under generated automatically no need for manual, manual update.
The dkim-about ' here: https://support.google.com/a/answer/174124?hl=hu