How to Back Up OLM File in Multiple Formats – Step-by-Step (2025 Guide)

Introduction

Let me guess — you’ve been using Outlook on your Mac for a while now, and everything was going fine until you needed to switch devices, save a backup, or simply access your emails on something other than Outlook for Mac. That’s exactly what happened to me a few months ago.

I had all my work emails, contacts, calendar entries — basically my digital life — stored in Outlook on my Mac. When I got a new Windows laptop from work, I realised I couldn’t just open my Outlook data like I used to. Everything was packed into this one file called an OLM file, and it didn’t work with Windows Outlook.

That’s when I realised: I needed to back up my OLM file and convert it into other formats that work across different platforms. Not just PST for Outlook on Windows, but also EML, EMLX, MBOX, etc, for other email clients and safekeeping.

At first, it sounded complicated — but it wasn’t. In this blog, I’ll show you exactly how I did it step by step. No need to be a technical specialist, no confusing steps. Just real talk. Before starting, what Mac OLM files are.

What Is an OLM File, and Why Back It Up?

An OLM file is a data file extracted from Microsoft Outlook for Mac, which contains everything from emails, attachments, contacts, calendars, etc. You can think of it as a large folder that carries all your Outlook data.

But here’s the catch: OLM files work only in Mac Outlook. They don’t open on Windows Outlook or any other email clients. That’s why backing it up in multiple formats makes your data usable, portable, and safe.

Example:

When I left my previous job, I needed my email history for reference. HR gave me the OLM file, but I couldn’t open it on my new Windows laptop until I converted it to PST.

Why Save OLM Files in Multiple Formats?

Each format serves a different purpose:

PST: Best for importing into Outlook on Windows.

MSG: Great for saving emails individually.

MBOX: Works well with Thunderbird, Apple Mail, and many other email clients.

EML: Saves each email individually, helpful for legal or support teams.

Saving in multiple formats ensures your data is not locked into one app or platform. It's about flexibility and future-proofing.

First Step: Export Your OLM File from Mac Outlook

Before you convert anything, you need the OLM Archive file.

Here's how I did it:

1. Launch your Mac Outlook.
2. Click on Tools > Export.
3. Click on what you would like to export (I clicked on everything).
4. Save the OLM file to a secure location such as Google Drive or an external USB drive.

Now that you have your OLM file, it is time to get down to the heavy lifting of backing it up in multiple formats.

Best Way to Create OLM Backup in Multiple Formats (Using Expert Tool)

This is where I found it easy. Instead of trying a complex & risky approach, I used a well-known, trusted program like OLM to PST Converter by Softaken Software for smoother and secure conversion of OLM files into multiple file formats (PST, EML, EMLX, MSG, MBOX, etc).

Why Expert Tool is the Best Choice:

• Using an Expert Software for conversion is fast, secure and saves lots of time.
• It supported multiple export formats: PST, MBOX, EML, MSG, etc.
• Support direct migration of OLM files to Office 365, Gmail, and any IMAP Server Account.
• Simple & easy to use interface.

Steps to Utilise a Professional Tool:

1. Install and open the OLM Converter program.
2. Browse and add the OLM files.
3. Select your output format(s): PST, EML, MBOX, etc.
4. Select output path for data.
5. Finally, Click Convert.

And that was it! In a few minutes, I had readable, usable backups of all my emails and all of their attachments.

Manual Methods (Time-Consuming & Risky)

I also explored some manual options, but honestly, they were more trouble than they were worth.

Method 1: IMAP + Gmail Trick

• Add Gmail to Outlook on Mac
• Sync emails to Gmail via IMAP
• Re-download them into Windows Outlook

This worked... kind of. But it was slow, risky, and some data could be lost during the process.

Tips for Choosing the Right Backup Format

Still unsure which format to pick? Here's what I learned:

• Use PST if you're going to use Windows Outlook.
• Use EML/MSG if you need individual emails for support/legal needs.
• Use MBOX if you're switching to Thunderbird, Apple Mail or any supported email clients.

Smart Backup Practices (Keep It Safe!)

Once you have your converted files:

• Keep one copy on an external hard drive.
• Upload another to Google Drive or OneDrive.
• Label folders clearly (e.g., Work_Emails_2025).
• Test your backup files before deleting anything!

Common Mistakes to Avoid

• Backing up only in one format (what if you can’t open it later?)
• Forgetting to back up
• Using unreliable or free tools that don’t preserve formatting

Conclusion

If you’ve made it this far — congrats. You now understand why it’s important to back up your OLM file in multiple formats, and exactly how to do it without the stress.

Trust me, I learned the hard way, but a tiny time investment today can save you hours of panic later.

So whether you're switching from a Mac to a Windows machine, leaving a job, or just being smart about your information — backing up that OLM file is probably a smart decision.

Get yourself the right Windows-based application, follow the steps above, and never be far from your emails.

Got questions? Drop them in the comments or reach out. Happy backing up!