KMail (Kontact) mail directory structure?

[homoludens1000]

Perhaps someone can enlighten me on how KMail managers its mail directories?

The mail data seem to be essentially stored in (for KDE 4, that is).: ~/.kde4/share/apps/kmail/mail

What I don't understand is where it stores its 2nd-level subdirectories. I usually archive emails according to the following structure:

Local Folders
   > Inbox
   > Outbox
   > (etc.)
   > Friends
      > Peter
      > Paul
      > Mary
   > Firms
      > Amazon
      > Naughty bits
    (etc.)

In .../kmail/mail, there are corresponding folders for the 1st-level entries, i.e.: inbox, outbox, Friends, Firms, but I can't find anything related to lower-level subfolders.

So far I also had problems when I tried to re-import kmail's mail folders (I would only get a certain number of emails with others missing), and I suspect this might have to do with the mail folder management(?).

[roberto60]

it depends on the type of mail folder you choose (it could be a file)
In my selection I have a directory named "Mail" under my home with the three you listed.

[homoludens1000]

Hmmm, in my example above, I have 1st-level folders (Friends, Firms) and 2nd-level folders / subfolders (Peter, Paul, Mary, etc.). I can see the folders for Friends, Firms under the /kmail/mail directory, but there is nothing (neither a folder nor a file) that is related to Peter, Paul, Mary, etc.

So, where are these folders (and the emails inside of them) stored?