1. From within Thunderbird go to: Tools -> Options -> Composition section.
  2. Select the "Directory Server" check box, and then choose the "Edit Directories" button.
  3. Choose "Add" to create a new directory server entry. Call it "Penn Online Directory".
    4. Fill in the Directory Server information:
    Name Penn Directory
    Hostname directory.upenn.edu
    Base DN ou=PennPeople, dc=upenn, dc=edu
    Port Number 636
    Bind DN uid=yourpennkey, ou=PennPeople, dc=upenn, dc=edu
  4. ^ Place your PennKey in the "uid" field.
  5. This is what everything should look like.
  6. Be sure to check the box that says to "Use secure connection (SSL)".
  7. Okay through the remaining windows, and close Thunderbird.
  8. The next message that is composed will try to auto-complete any name entered into the "to" field.