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File Extension
Application Category & Support
Owned by Organization
Supported Operating Systems
File Location
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Understanding What is OLK File Extension?


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 (Offlice 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.

  • Outlook 2011 for Mac
  • Outlook for Mac

Microsoft Corporation

  • 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
  • Corrupted or inaccessible file.
  • The required software to view the file is not installed or even corrupted.
  • The version of compatible application is not correct.
  • Invalid registry key entries.
  • There is some bugs created issues with opening OLK file.