An MBOX file saves email messages. If you are suffering from how to open MBOX files, read this write-up and get the best free MBOX viewer tool for your purposes to simply view the email data.
Shoviv MBOX Viewer software is an open utility. The MBOX viewer allows recovering corrupted MBOX files and resolves the user’s query “how to open MBOX files” without hitches.
Highlights:

Add multiple Corrupted/healthy MBOX files.
Open MBOX Files with Attachments.
Keeps MBOX Folder Hierarchy.
No need for any email clients.
User-friendly GUI.

Helpful utility for you where you are searching how to open MBOX files.
Read more: How to Open .mbox file