Manually add DKIM public and private key to your cPanel/WHM server
There would be some cases when you would need to add a custom DKIM key. This doesn't happen often as cPanel has automated the procedure, however here are a few simple steps that you need to follow in case you need to set that up.
Generate a Domain key
If needed you can generate the key via this or any other site:
Find the location of the domain keys folder in exim
Edit the exim conf and look for DKIM.
There you should see the path were the keys are stored example:
Updating the domain keys
Find the domain in question and update the DKIM private key there. For example I would say that my domain is bobbyiliev.com
Add the private key to:
Add the public key to:
Setting up your DNS
You will need to add a record to your DNS server with the public key as standard.
To be on the safe side just give your exim instance a quick restart so that you would be sure that exim would read the new DKIM.
Hope that this helps someone.