The mbox source format in Aid4Mail will work for Apple Mail, but there is a procedure to follow.
The .mbox "files" that Apple Mail exports to are not really files, they are folders. Inside the folder you will find the actual mbox file, usually just called "mbox". That is the file you need to process.
However, Aid4Mail can process Apple's native EMLX mail file format, meaning you do not have to first export to mbox. Just use the "Apple Mail" option on Aid4Mail's Mail Source screen.
If you experience any issues, please don't hesitate to contact us by raising a ticket.
If you would like to buy an Aid4Mail license, visit the Aid4Mail website.