To authorize Namecheap Private Email to send emails on your behalf you will have to include it in your SPF record. The SPF record mechanism used is shown below.
For more information on SPF set up for Namecheap Private Email please click on the button below.
For information on how to set up DKIM please contact Namecheap support and they will generate the DKIM key for you.
Create a free OnDMARC account to test your configuration.