• Click "Mail" in the menu bar.
• Click "Preferences".
• Click on the "Composing" tab.
• Check the box next to "Automatically complete addresses
• Click on the "Configure LDAP..." button
• Click on the "+" button
• Fill in the following information:
  Name: ldap.wvu.edu
  Server: ldap.wvu.edu
  Port: 389
  Search Base: ou=people,dc=wvu,dc=edu
  Scope: Subtree
  Authentication: None
  
• Click on the "Save" button
• Click on the "Done" button
• Close the preferences window.

To use the feature where LDAP is searched, create a new message by choosing New Message from the File menu. Enter part of a name in the To: line. The client will do an LDAP lookup, present a list of results, and complete it once you select a name from the list of results.