Reference from https://support.google.com/mail/answer/21289?hl=en? on Sep 11, 2020
If you have multiple webmail or other provider email accounts, you can check them all in Gmail.
Gmail first imports all your old messages to Gmail and then continues to bring in new messages sent to your other account.
You can add up to 5 accounts, including Gmail and other email providers.
- Open your Gmail account.
- At the top right, click the gear Settings.
- Select Settings.
- Select the Accounts and Import tab.
- In the "Check mail from other accounts (using POP3)" section, click Add a POP3 mail account you own.
- Enter the full email address of the other account, then click Next Step.
- Enter your password.
Now you have a few options to choose from.
Here's our recommended settings:
- Leave a copy of retrieved messages on the server - Uncheck the box.
- Always use a secure connection (SSL) when retrieving mail - Keep checked. For some accounts, you may need to uncheck this option.
- Label incoming messages - Check the box if you'd like to easily see which emails in your inbox came from this account.
- Archive incoming messages - Don't check. Only check if you don't want to see new messages from the other account in your inbox.
Click Add Account.
If you get an error message while getting set up, click the Show error details link to find out more about what's not working.
For other errors, visit Problems with Mail Import troubleshooter.
Once your account has been added successfully, you'll be asked if you want to be able to send mail as this address.
This lets you compose messages in Gmail, but have them appear to be sent from your other email account. Gmail will check your other account for new emails periodically.
You can see when the other account was last checked from the "Accounts and Import" tab.