dovecot - Jan 2015 - Trying to get lda to deliver into public sub-sub-folder

Hi,
I have this setup:

recipient_delimiter = +
mail_location = sdbox:~/sdbox
namespace {
  type = public
  prefix = public/
  location = sdbox:/home/vmail/shared/sdbox
  subscriptions = no
}

Postfix delivers via dovecot-lda:
dovecot_shared unix    -       n       n       -       -      pipe
  flags=DRhu user=vmail:vmail argv=/usr/bin/env HOME=/home/vmail/shared
/usr/lib/dovecot/dovecot-lda -f ${sender} -m ${user}/${extension}

This works fine, ACL are manually defined and also work great.
If I want to deliver into a subfolder I tell postfix to rewrite it to:
folder+subfolder at dovecot_shared
This is how it looks like:
/home/vmail/shared/sdbox/mailboxes/{user}/{extension}/dbox-Mails

But with this setup I couldn't get it to deliver into a subfolder of
"subfolder/extension".

Is it at all possible? Changing the HOME directory does not work because
of the sdbox folder structure.

I tried to generate a service for each subfolder like that:
-m ${user}/subfolder/${extension}

But when I did not have an extension I got:
save failed to open mailbox {user}/subfolder/: Invalid mailbox name
even though it exists. I think it doesn't like the trailing slash, but I
don't know how to get rid of it.


Hope I explained it well enough :)

Regards,

Claudius