Email Security for Thunderbird
1. Open Thunderbird, go to Tools -> Account Settings.

2. Click Server Settings to the left. Enter your FULL email address for the User Name.

3. Click Outgoing Server (SMTP) on the right. Select the outgoing server by clicking on it, then click the Edit button.

4. Under Security and Authentication, select the "Password, transmitted insecurely" option.

5. In the User Name field, type your FULL email address and click Ok.