To add public folder contact lists to the Outlook Address Book, please use the following instructions. The screenshots in this article are using Outlook 2010. Outlook 2013 or 2016 may look slightly different.
1. Open the 'folder view'
Click the folder icon at the bottom of the left hand column in Outlook.
2. Expand Public Folders
Look for 'Public Folders' followed by your email address in the list and click the triangle to expand the folders list, then do the same for 'All Public Folders'
3. Select the contacts list
Find the contacts list you want to add. Right click the list and select properties.
4. Add to the Outlook Address Book
Click the 'Outlook Address Book' tab and check the box for 'Show this folder as an e-mail Address Book'. Click OK.
5. Open the Outlook Address Book
The contact list will now show in the Outlook address book in the drop down box.