In Thunderbird select Tools -> Account Settings
Once in Account Settings select Add Account...
Select Email account and click Next >
Under Your Name: enter your first and last name
Under Email Address: enter your username@csulb.edu
Select IMAP
If you would still like to use POP, please refer to POP3 or IMAP
Incoming Server: imap.csulb.edu (or popmail.csulb.edu)
Click on Next >
For Incoming User Name: enter your CSULB Internet Account username
For Outgoing User Name: enter your CSULB Internet Account username
Click on Next >
Under Account Name you can enter an alias for the account, the default is fine in most cases
Click on Next >
When presented with the Congratulations click on Finish
Finally select Outgoing Server (SMTP) from the left pane.
For Server Name: enter smtp.csulb.edu
For Port: enter 587
Check Use name and password
For User Name: enter your CSULB Internet Account username
For Use secure connection: select TLS
Click on OK