Importing mail from Windows10 'MAIL'

Typical for MS Windows, one day or another their mail program crashes. So i’m taking over my wife’s PC for a few hours, instakled eM Client (the program i’ve been using myself for rather some time).

On her PC she has Win10 and a MS mail program called just ‘mail’, however when trying to import the mails received with ‘mail’ i seem not to be able to import them to eM Client. The storage location seems ok but I seem to look for the wrong formats…eml, pst, ost etc

Who knows ?