Your old e-mail messages can be imported into Gmail as long as you haven't deleted them from the mail server. This way, you can store all of your old messages in Gmail for later reference, while receiving new messages at your new Gmail address.
Click on the Gear icon in the top right corner and Go to Settings
Click on the Accounts and import, then under "Check mail from other accounts (using POP3)," click "Add a POP3 mail account you own."
Enter the e-mail address of the account you want to migrate (your old e-mail address).
Enter the password for the e-mail account you're migrating, as well as your e-mail provider's POP server name and port number. For example:-