Upgrade from Windows Vista to Windows 10 – How to Restore My Old Mail from WLM?

Hello. I recently helped my grandparents upgrade their PC from Windows Vista to Windows 10. We backed up all of their files on an external hard drive and I've also looked at the Windows.old folder Windows 10 made after installing. I need to be able to open their old saved Windows Live Mail inbox, outbox, sent messages and contacts. I have found them in "C:\Windows.old\Users\(name)\AppData\Local\Microsoft\Windows Mail" but cannot open them with Windows 10's Mail program. When I try to open WinMail.exe to open the old program, it gives an error stating: "Windows Mail could not be opened because one of it's libraries cannot be found".

How can I get the inbox, outbox, sent messages and contacts back?

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