Where does the Windows 8 Mail App store data?

Solution 1:

Yes it does, if you go to C:\Users\<username>\AppData\Local\Packages\, open the folder that starts with "microsoft.windowscommunicationsapps", open the folders \LocalState\Indexed\LiveComm inside that, then select the folder with the email you want to look at, then one folder down you'll see two folders, "Mail" and "People". Select the one you want, and then a few more folders down you'll .eml files for each of it's stored emails/contacts.

Solution 2:

For anyone who upgraded to Windows 10..

I had almost finished a (lengthy) draft email when I decided to upgrade from Windows 8.1 to Windows 10. After the upgrade, my 'old' email app was gone, and as I opened the new email app my draft was gone.

Fortunately, I found the mail as the most recent .eml file in

C:\Users\Username\AppData\Local\Packages\microsoft.windowscommunicationsapps\LocalState\Indexed\LiveComm........

just as MatthewThepc described.