Start Mozilla Thunderbird, and click the "Tools" menu. If you don't see the menu bar, press the Alt key on your keyboard to show it temporarily. To have the menu bar shown all the time, right-click on an empty section of the Tab Strip and check Menu Bar in the pop-up menu.
In the "Tools" menu, select "Account Settings". The "Account Settings" window appears.
Click the "Account Actions" button and select "Add Mail Account...". The "Mail Account Setup" window appears.
Enter your name as you'd like it to appear on the "From" line of your outgoing email messages. Enter your full email address and your email account password.
Click "Continue", then click the "Manual config" button which will appear in the lower left corner of the window. Note: Thunderbird might find a configuration by trying common server names, but don't click "Done" or "Create Account" just yet! Click "Manual config". The window expands with additional settings.
Set the incoming server type to "POP3".
In the "Server hostname" field enter securemailserver.ca for both the incoming and outgoing server.
In the "Username" field enter your full email address.
Click the "Re-test" button. The "Port", "SSL" and "Authentication" settings should now be set automatically as shown in this image:
Click "Done" or "Create Account".
Click "OK" to close the Account Settings window.