The method is simple and straightforward and you will use some Gmail account settings that will allow you to forward all emails to another account. And it's a Gmail feature that no one of you ever knew before reading this guide. So, follow a few simple steps below.
Steps to enable POP in an old email account to import emails to a new account:
1. Log in first to your Gmail account whose e-mail address you want to transfer to another account.
2. Now click on the settings button below your profile picture of your account.1
3. Now in the settings, click the option Transfer and POP / IMAP and there enable POP Enable for all messages (even mail that has already been downloaded).
4. In the list below, select Copy as read from the drop-down option in Gmail, and then simply click the Save Changes option.
5. Now, visit your new Gmail account to which you want to receive all your mails.
6. There, click Settings and under Accounts and Import and select Add a POP3 E-mail Account You Own,
7. Now a pop-up window will appear where you have to enter the email address from which you want to import emails, then click on the next step.
8. Now, on another page, simply continue by entering the password and all other fields will be filled in automatically and simply click Add Account.
9. Now, on the next screen, just click on the option yes and click on add
10. That's what you did, now all emails from this account will be there in your new Gmail account.