Step 1: Log into your Gmail account.
Step 2:Go to the Gear at the top right and select Settings.
Step 3:Click “Accounts and Import”
Step 4: Click Add another email address you own option
Step 5: Enter your domain’s email address and click Next Step.
Step 6: On the Send mail through your SMTP server page, fill in your SMTP Server (typically “mail.domain.com”), Username (full email address), and Email Password. Then, click Add Account.
Step 7: Now, Gmail will email a verification code to the address you just added. Check your domains email for a message Gmail sent you. Click the link in the email, or Enter the code into the text box and click Verify.
Step 8: Now you will see your Domains email address in the Send Email As and the Check mail from other accounts section.