Looking for an application which can read Thunderbird archived files

So I have set up Thunderbird to include a Local Folder on my hard drive on which I copy email folders I want to archive safely. I can find Local Folders on my hard disk, and within that a folder called "Archive.sbd". That in turn gives access to documents called, for instance, "emails.2021" and "emails.2021.msf". The problem is that opening document "emails.2021" leads to an unusable mass of binary code. The archived documents can of course be opened through Thunderbird itself, but is there any Mac application which read such files independently of Thunderbird?