1. Open Mozilla Thunderbird 3.0 by either selecting the “Mozilla Thunderbird” icon from the Windows “Desktop” or by selecting the “Mozilla Thunderbird” icon from the “Start” menu.

2. Select "Accounts Settings…” from the "Tools" menu at the top.

3. The Mozilla Thunderbird "Account Settings” dialog box will now appear. Click on “Outgoing Server (SMTP)” in the left window pane with your mouse button.

4. In the “Outgoing Server (SMTP) Settings” window, click on the edit button on the right hand side.

5. In the “SMTP Server” window, change the port to “587,” then press the “OK” button at the bottom.

6. Finally, click on the “OK” button on the bottom of the “Account Settings” window and your new settings have been saved.