Google apps have been discontinued as free service. So you might have challenge in finding right mail service which is free and offers comprehensive email hosting solution for your custom domain name. Outlook.com or Microsoft offers such service. Here I am giving you step by step method to setup email on outlook.com for your custom domain.
Create Microsoft login account at www.live.com if you have an existing account you can use it
Go to www.domains.live.com below screen will show up, click on get started
Add your custom domain for which you want to setup outlook mail service
Click on domain name account
Now login to your web domain registrar’s website and create the MX entry for your domain
You need to make MX record as follows:
DNS record type: MX
MX server: cf2bf9e284ff478ee6619c86e8d798.pamx1.hotmail.com
TTL: 3600 or 1 hour (optional)
Priority: 10 (or High priority) (optional)
Go to www.domains.live.com and click on the domain for which you changed the settings. Refresh to see if the MX record propagation is successful (this might take 0-24 hours).
After successful setup the status will become as “Active”
Now you can add mail usernames for your custom domain.
Now you can start adding users to your custom domain like firstname.lastname@example.org etc.
To check emails, send emails go to www.mail.live.com and use your email@example.com and password selected during adding username.
Outlook Detailed Instructions: