Follow the steps to understand the Mac Mail Migration tool
Install and Run the Mac Mail Converter software
Select Mac Mail files or folders having Mac Mail files
View source path of selected folder
Choose all required mailbox folders or items displayed
Select required option from list of 25+ saving options
Setup Mac Mail conversion options like Destination Path
Click On Next button & analyze Mac Mail conversion process
Click on OK button to confirm & exit from here
Obtain the resultant files directly from destination path
Open resultant file in supported email client