1) Open Microsoft Outlook

2) Click on the "Tools" menu, up at the top of the screen. (figure 1)

Figure 1 - Main Thunderbird Screen

3) Click on "Email Accounts..." (figure 2)

Figure 2 - The Tools Menu

4) This will pop up a new window. On here, select "View or change existing account (figure 3, number 1) and then hit next (figure 3, number 2)

Figure.3 - E-mail Accounts

5) Highlight (click on) your account and click the "Change..." button. (figure 4)

Figure 4 -E-mail Accounts

6) Click on the "More Settings..." button (figure 5)

Figure 5 - E-Mail Accounts- details

7) Click on the "Outgoing Server" Tab at the top

8) On here you will find a check box titled "My outgoing server (SMTP) requires authentication" Place a check mark in that box, then hit the "OK" button (figure 6)

Figure.6 - Internet E-Mail Settings (more settings)

9) that will bring you back to the Email Accounts window. Click the finish button here.

Figure.7 - Back to E-mail Accounts