If you think that the cPanel email is slow. Then I recommend trying out Yandex. You first sign up and create an account and organization. Then you go to admin and add your domains (the first one is the main domain the others are aliases). After that you add their MX record, SPF, and DKIM records. Click add a person and fill in the mandatory info and write your email and passwords. Voila, you got yourself a fast and free domain email (that you can connect to Gmail or Microsoft 360). P.S the limit is 1000 email accounts and 10 GB each.