If you are looking for setting up domain based email accounts, Pixpa recommends Google Business Email service thats based on the popular Gmail platform.
To learn how you can setup Google Apps Email for your domain name, see this help article by Google: https://support.google.com/quickfixes/answer/6252374?hl=en
As part of the email setup process, Google will ask you to verify your domain name. In that case, choose the verification method by Meta tag method.
Then go to the Settings section. Go to the External Scripts page and paste that copied meta tag and click on Save.