When it comes to email providers, there's no competitor to Google's awesome features. It is efficient which connects seamlessly with the rest of your Google products such as YouTube, Drive, has a major application called Gmail Inbox, and is overall an extremely powerful email service. However, to use it with a custom domain, you need to purchase Google Apps for either $5 or $10/month, which for casual users is a bit unnecessary. On top of that, you don't even get all of the features a personal account gets, e.g. Inbox. So, here's a free way to use your Gmail account with a custom domain. I am just going to show you hacking Gmail for free custom domain email.

STEPS:

• First, register with Mailgun using your Gmail address. Use your Gmail only. Once you have clicked the confirm link, log in to the Mailgun website. Now you're in the dashboard, move on the right under "Custom Domains", click "Add Domain".
• Follow the setup instructions and set DNS records with whoever manages your DNS. Once you've done this, click on the "Routes" link on the top to set up email forwarding.
• Now move to the Route tab and click on Create New Route.
• As you click the button, you will see a page like below. Just enter the information as entered in the following screenshot.
• Just replace the quoted email with your desired email in the above-given screenshot.
• Next, we'll setup SMTP configuration so we would be able to send emails from an actual server. Go to "Domains" tab, click on your domain name.
• On this page, click "Manage your SMTP credentials" then "New SMTP Credential" on the next page.
• Type in the desired SMTP credentials. And, go to Gmail settings and click "Add another email address you own". Once you open, enter the email address you wish to send from.
• In the next step, set the SMTP settings as follows.
• After clicking "Add Account" button, now you're done.
• The final step, make sure to set it to default email in the Gmail settings > Accounts.