Gmail has built-in functionality that allows you to check emails from external accounts using the POP3 email protocol. To add an email hosted here in your Gmail interface, follow the steps below:

Incoming Mail Configuration

• Sign in to your Gmail Account.
• Click the gear icon -> See all settings.
• Go to Accounts and Import.
• Under the section Check mail from other accounts, choose Add a mail account.
• Enter your Email address (e.g. user@yourdomainname.com).
• Click Next.
• Username: enter your full email address (e.g. user@yourdomainname.com)
• Password: enter the password for the above email address
• POP Server: The Secure SSL/TLS server settings are listed in Site Tools > Email > Accounts > Manage Email Accounts > Actions > Mail Configuration > Manual Settings.
• POP3 port: 995
• Leave a copy of retrieved message on the server can be selected if you wish to save your messages on the server as well.
• Check Always use a secure connection (SSL) when retrieving mail.
• Click on Add Account.

Continue with the SMTP server setup if you want to send mail from your email address:

Outgoing Mail (SMTP)

• Select Yes, I want to be able to send mail as user@yourdomainname.com
• Choose if you will use this address as an Alias.
• SMTP server: Use the same secure server as you did in the incoming settings configuration.
• SMTP port: 465
• Username: enter your full email address (e.g. user@yourdomainname.com).
• Password: the password for this email account.
• Check the Secured connection using SSL option as well.
• Click on Add Account.

Gmail will send you a verification email that you have to approve, so you can use the SMTP functionality.