Where does Mail 10 store emails & in what file format (it's not .eml!)

Yes, I know, I have Seagate's tools, and various others for cloning discs.
My issue is still the data store though, and the file format.

Not to be too cheeky, but in this very thread you said "Mail's messages are stored locally on a mail folder in the hidden AppData folder as .EML files
See folder
C:\Users\<username>\AppData\Local\Packages\, choose microsoft.windowscommunicationsapps, and open the folder \LocalState\Indexed\LiveComm. Find the "Mail" folder and open it. You should see your .EML files"

I know things change, but thats my point about linkrot. MS do try to write documentation, not just blog posts like some providers, but even MSDN is full of outdated information and screenshots. I NEED to ensure that I back up all the mail data, but as far as I can tell these dat files are not the emails I see in W10 mail .
Puzzling.

Any criticism I expressed was directed to Microsoft (not that they will be watching). The developers wont have made this change at random, a Business Analyst / Program Manager will have raised a change note, any change to the storage location would obviously involve data migration on existing installations, so QA would need to be told where to look etc. etc. Surely SOMEONE could have told the Technical Authors / documentation team?

(I used to try and manage a team of web developers, I know from experience getting a developer to write documentation is a lost cause)

OMG, I think that article on Elsevier has the answer. The other folders under appdata\local\comms do look like a file-oriented database, like SourceSafe but without the versioning.

That said, I think I have been wasting my time (and yours). My family member is non-technical (and remote) and uses the word "email" to mean the thing she reads, the service that delivers it and the application that displays it. It turns out she uses firefox to get on to the academic webmail system and reads the mail in the browser. Next time I go over there I'll do a tutorial.
I am intrigued that those .Dat files appear to be UTF-16 html, I recognise some of the text in them as things I have seen / sent, but what generated them... and I cant read them in Visual Studio's binary editor if I select that encoding.

In case anyone else reads this, It seems the byte order mark may be incorrect. The first two characters in the file 0xFE 0xFF indicate UTF-16 Big Endian but if I tell VS to open it using "HTML editor with encoding" thus:

then choose "Unicode-big endian - codepage 1201"

The file is displayed as a single line of Chinese characters.

If I instead choose codepage 1200, I see the html text... this one appears to be a zoom meeting invitation...which came in on my Outlook mail company account, nothing to do with the Windows 10 mail app at all.


Thanks for your time and those very handy links.
Ten points to Griffindor

@Legacyofherot

After I copy the .dat files to a separate folder and I rename their extension to .html I can drag 'n drop them into my Firefox browser window just fine.

Hmmm, I didn't try it in Firefox, just edge. I suspect Firefox is ignoring the byte order mark and just displaying the UTF-16 characters.
Anyway, I still don't know what creates the .Dat files - they are not the emails I can see in W10 Mail app.
Weird, but I have more entertaining things to get on with.
/B