If you’ve moved away from using Outlook for Mac then you’ll likely have some OLM archives stored within a folder somewhere that you can no longer open. As OLM is specific to Outlook for Mac it can be seen as a locked safe on Windows. So by installing Outlook again you will have to rebuild an entire profile to view your old emails.

All workarounds for this issue have some drawbacks. Installing Outlook can be quite intensive and may cause issues with your original archive. Importing into another client will alter your data which may not be desired for a business archive. Using online converters will require you to upload your years of emails to another server.

What you really want is to view your old archive without any conversion.

This is where Kernel OLM Viewer comes into play. It is a completely free application that allows you to open your OLM files straight onto Windows (this is usually the issue). It will also allow you to open corrupted or damaged files without having to repair them first. You are able to open multiple archives and view your emails, attachments, contacts, calendars and tasks in their original folder structure.

https://www.nucleustechnologies.com/olm-viewer.html

How are you dealing with your old OLM files?