Thunderbird is a popular open-source email client from the Mozilla team. You can download Thunderbird for free here:

https://www.thunderbird.net/en-US/

After installing, start Thunderbird and look for the “Set up an account” in the “Accounts” section of the home screen. Click the “Email” item.

The “Set Up an Existing Email Account” dialog will be displayed. 

Enter your name, email address, and password and click the “Manual config” button to move to the next screen.

Enter “mail.reliablepenguin.com” in the “Incoming Server Hostname” field and the “Outgoing Server Hostname” field.

Enter your full email address in both of the “Username” fields at the bottom

Leave all other fields at the default settings. 

Click the “Re-test” button. If the test fails then double check the server names and your email address. Also make sure you are typing your password correctly. Make sure you don’t accidentally add extra spaces before or after any of the fields.

Once the test completes successfully then click the “Done” button to finish the setup.

Setup is now complete and you’re ready to send and receive email. Contact support if you need assistance with this setup.