MBOX files are commonly created by email clients such as Thunderbird, Apple Mail, and other applications, so opening them directly can be difficult if the original application is no longer available. One option is to use an MBOX viewer that can read the mailbox data and display emails with their folders and attachments. Before working with the file, it is also a good idea to keep a backup of the original MBOX. SysTools MBOX Viewer can be considered when you need to access and read MBOX emails without depending on the original email client.