To set up your Gmail account to receive emails from a POP account, please follow these steps:

Step 1.
Login to your Gmail account, click on the gear icon at the top right corner of the page, then click Settings. Next, click Accounts and Import.

Step 2.
Under Check Mail From Other Accounts, click Add a POP3 mail account you own.

Step 3.
Enter your hosted email address, then click Next Step.

Step 4.
Ensure that your username is your full hosted email address, then enter the password for your email address. The POP server should be mail.yourdomain.tld (ex: mail.example.com) followed by Port number 110.

Step 5.
Do not select Always use a secure connection (SSL) when retrieving mail. Leave this empty.

Step 6.
Click Add Account.

To send mail from your Gmail account under your hosted email address please follow these steps:

Step 1.
Login to your Gmail account, click on the gear icon at the top right corner of the page, then click Settings. Next, click Accounts and Import.

Step 2.
Under Send mail as, click Add another email address you own.

Step 3.
Enter your name and hosted email address. Check the box to Treat as an Alias, then click Next Step.

Step 4.
The SMTP server name is mail.yourdomain.tld (ex: mail.example.com) followed by your username (full email address) and password for your email address.

Step 5.
The port number must be 25. Ensure that the options for TLS or SSL are not selected.

Step 6.
Click Add Account.

After you have completed these step Gmail will send you a verification email containing a link and password. You will be required to activate the account by following the steps in their email.

Once your email address has been activated to your Gmail account you will be able to send email in Gmail through your hosted email address.