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To access these emails, go to g.ucla.edu and sign on with your UCLA logon (1 below).
To access Google through a program other than a web browser, you need to set up a Google Apps password; click 2 above, then click "My Google Apps username or password"
You will then be able to create a password for use with Thunderbird, and other software.
Thunderbird settings
Go to Account Settings (Tools menu, or right-click over an account on the left)
Under Account Actions, click "Add Mail Account"
Enter your name, and jbruin@g.ucla.edu as your email address, then your Google Apps password.
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