What is OLK15message files and how to recover it? Can anyone explain to me what is an OLK15message file, what it has to do with Outlook 2016 for mac? Actually, my outlook mac database got corrupted and someone told me that Outlook Mac stores its database in OLK15 message files. Is that so? If yes then how can I recover OLK15message files in order to restore my Outlook 2016 for Mac? 

Please keep the explanation basic as I am not at aware of complex technological terms. Thanks
Apart from OLM files, Mac Outlook creates temporary files in the backend called as OLK file. These contain data exclusively related to individual profiles. It is stored in the identity folder of the respective profile to which it relates. The OLK file only stores the header information of the mails data. For storing message content without attachment Mac Outlook Creates OLK14/15MSGSOURCE. 

The location of OLK Files:
[user]/Documents/Microsoft User Data/Office 2011 Identities/Main Identity/Data Records/Messages Source

Its recovery is a bit risky one but here's an article that explains how to recover OLK15message files: http://olk15messagerecovery.blogspot.com/