My Outlook for Mac mailbox had become quite large, and it was starting to feel sluggish. Since I also wanted to move my emails to another email client, I decided to Convert OLM to MBOX File instead of keeping everything in OLM format.

I used MacSonik OLM Converter, and one feature I appreciated was the ability to preview the mailbox before starting the conversion. It also offers filters if you only want to export specific data instead of the entire archive. The conversion finished without affecting my email folders or attachments, and the MBOX files imported into my new email client without any issues.

Overall, it was much easier than going through the manual Outlook method, especially for a large mailbox.
link-https://www.macsonik.com/blog/how-to-migrate-olm-to-mbox-mac/