We may have more than one mail account and we may use only one email account to receive emails from different account. Once we receive email to one account then we can set an option to forward to another account automatically.
1. Login to Gmail.
2. Click on "Settings" in top right corner.
3. Click on "Forward a copy of incoming mail to" and enter your primary email where you want to auto forward.
4. Shortly you will receive a confirmation code to that email id.