[Evolution] Where to store local accounts?

[Ángel <angel 16bits net>]

Hello all

Today I have an adventure to share about creating external accounts.
I wanted to file certain mails in a (different) local account. To this
end, I added a new maildir account. Given that it needs to point to an
existing folder, I decided to create it as a subfolder of
~/.local/share/evolution/mail, which turned out to be an error.

evolution-data-server then moved that folder to
~/.local/share/evolution/
mail/trash/ on next restart (then failed to find the new account).

Yes, it is a private evolution folder. The user is not supposed to
tweak with it. Still, I was a bit puzzled by the behavior.
I could have stored that maildir on ~/Documents or ~/Desktop but I
precisely wanted it to live within the other evolution folders. As a
sibling of local/ (the store for the 'On This Computer' account) seemed
the perfect place (the folder name itself would not conflict with or
protocol).
Diving into this, it seems that there is a cache-reaper getting rid of
unexpected cache and data dirs.

I guess I could achieve the original goal by moving the maildir inside
its source folder (a catch-22, since the maildir needs to exist before
creating the source it can only be done later). The question is, which
would have been the "proper place" to locate such folder?