There is only one file type that uses the .OLK14MAILACCOUNT extension:
Outlook Mail Account File
File created by Microsoft Outlook for Mac, an email application first released for Mac in the 2011 edition; stores email account settings, including connection and login information; used for storing the account details that allow users to download email and synchronize calendars.
Outlook automatically saves account information to OLK14MAILACCOUNT files within the following directory in Mac OS X:
[user]/Documents/Microsoft User Data/Office 2011 Identities/Main Identity/Data Records/Mail Accounts/
|Microsoft Outlook 365||Free+|
Updated: March 6, 2011