The OLK file extension is an acronym for Outlook Address Book, associate with Mac Outlook and introduced by Microsoft. The .olk files are used by Mac Outlook email application to store address book information for people and organization such as phone numbers, names, addresses, company data and other contact information.

• Outlook 2011 for Mac uses two files for storing emails i.e. OLK14MESSAGE and OLK14MSGSOURCE.
• Outlook 15 for Mac (Office 365 subscribers) uses OLK15MESSAGE file.
• OLK14Message file saves header information of emails.
• OLK14Msgsource file stores email body information.
• OLK14Category file saves the categories as Personal, Family, holiday.
• OLK14Event stores the event information such as time, date, visitors.
• OLK14Contact file is used to save emails, names, phone numbers.
• OLK14Signature file saves mail signature of Mac outlook profile in HTML format.
• OLK14Mailaccount consists of account information such as login details

The file extension for Outlook Address Book is *.olk.

The OLK file extension can be classified under Database files.

The following applications create OLK file.

Microsoft Corporation

application/octet-stream

Mac OS X

• OLK14MSGSOURCE – Username\Documents\MicrosoftUserData\Office2011Identities\MainIdentity\Data Records\Messages_Source\OM\OB\OT
• OLK14Message – Username\Documents\MicrosoftUserData\Office2011Identities\MainIdentity\Data Records\Messages\OM\OB\OT

OLK file can be opened using Outlook for Mac and its various versions or free tools mentioned below.