File Extension OLK File Format Microsoft Outlook address book OLK stands for Microsoft Outlook address book. This was last updated in March 2012 By Margaret Rouse Browse File Extensions Alphabetically: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ask a Question. Find an Answer. Ask your peers a question about this file extension. Ask a Question Can I replicate an Outlook address book to a BlackBerry address book? exchange 2003 for calendar but email is POP3; create a meeting using pop3 account; outlook 2007 How can i export address book located on outlook express, and use it in exchange 2003 global address book?