How to verify DKIM records are working

Use the following steps to verify your domain's DKIM records are working:

1. Use the Email Deliverability interface in cPanel to confirm that the correct DKIM record exists in your domain's DNS zone. If you are checking the DKIM for your server's hostname, use the Email Deliverability interface in WHM instead. If you prefer using the command-line over the cPanel/WHM interface, you may use the validate_current_dkims API call which performs the same check as the Email Deliverability interface. 
2. If either of the above methods detects an invalid DKIM key, cPanel will not sign that domain's outbound email with a DKIM signature to avoid a DKIM failure. You will need to take steps to correct the DKIM in the DNS zone based on the output from Email Deliverability/validate_current_dkims.
3. Once the DKIM is valid, cPanel will sign the outbound email with DKIM. You may verify the validity of the DKIM record with a third-party tool such as https://dmarcian.com/dkim-inspector/.