Mac OS X version up to 10.4 LDAP Setup Instructions

In Mac Mail, select the Mail > Preferences...

Click on the Composing button at the top then select Configure LDAP...

Next, fill in the boxes correctly:
Name: CSULB LDAP
Server: ldap.csulb.edu
Search Base: o=csulb
Port: Place a check mark on the box labeled Use SSL then change the port to 389
Username: uid=username,o=csulb
Password: password
Click Save when you are done.

Then, go to File > New Message.

Type the name of the individual in the To: field and the email address of the matching people will come up.
Mac OS X version 10.5 LDAP Setup Instructions

Open your Macintosh HD and select Applications. Then, open your Utilities folder and double click on Directory Utility.

Next, you will need to authenticate yourself. If the lock at the bottom-left hand of the screen is closed, click on the lock and then enter in your password and press OK. (If the lock is open, you can skip this step).

Click on the Edit menu and select Enable Root User. You can then close the Directory Utility. (If you already have enabled your Root user account, you can skip this step).
Now open the Terminal application inside your Utilities folder.

Once the terminal window is open, type "su root". This will log you in as the root user (Administrator) of your computer. Note: the root user should only be enabled if you need specific access for certain operations.
Now type in the root user's password. You will not see what password you are typing. If you do not remember your root user's password, you can go back into the directory utility and change it.

Once logged in as the root user, type 'vim /etc/openldap/ldap.conf' to open up the LDAP configuration file.
Using the arrow keys, move to the last word of the last line 'demand'. Now, hit the 'Insert' or 'i' key on your keyboard.
Press the delete key to delete the word 'demand' and then type in the word 'never'.
Next, press the Escape (ESC) key and type in ':wq' to save the file and exit. Then close the Terminal window.

Open your Mail program either by clicking on the icon on your Dock, or by going into your Applications folder.
In Mac Mail, select the Mail > Preferences...

Click on the Composing button at the top then select Configure LDAP...

Next, click on the '+' icon to add an LDAP account.

Next, fill in the boxes correctly:
Name: CSULB LDAP
Server: ldap.csulb.edu
Search Base: o=csulb
Port: Enter in 636 for the port number and place a check mark on the box labeled Use SSL and on Allow self-signed cerificates.
Authentication: Change the authentication from None to Simple
Username: uid=username,o=csulb
Password: password
Click Save when you are done.

Now click Done to exit the LDAP configuration and close the Composing Window.
You will need to restart Mac Mail. Go to the Mail menu and click Quit Mail. Then, reopen Mac Mail again either in the Dock or through the Applications folder.

Go to the File menu and select New Message.
Finally start typing a name into the To: field and the names will come up as shown above.