1. Launch Thunderbird
2. Click the "Alt" key on your keyboard, then select the "Tools" menu and choose "Account Settings".
3. Click "Account Actions" on the left side, then select "add mail account"
4. Enter in the following as prompted:
Name: Your Name
Email address: firstname.lastname@example.org
Once done, click "Continue"
5.Thunderbird will automatically suggest that the mail account is IMAP. This is INCORRECT. After Thunderbird finds the configuration, change the option from IMAP to POP, then select Manual Config
6. Enter in the following as prompted
Incoming server hostname: mail.domain.com
Incoming port number: 110
Incoming SSL: DO NOT USE SSL
Incoming Authentication: Normal Password
Outgoing SMTP server hostname: mail.domain.com
Outgoing SMTP port number: 26
Outgoing SSL: DO NOT USE SSL
Outgoing authentication: Normal Password
7. Before continuing, click on "advanced config"
Click on ‘server settings’ from the list of options on the left
Here you can specify how often you’d like Thunderbird to fetch new mail in the setting “check for new messages every X minutes”
You should also specify to leave messages on server for at least 10 days
8. Click "OK" and complete the setup!