[Dovecot] Folders within folders ...

[Ashley M. Kirchner]

   Our mail setup is as follows:
   ~/mail/ - This contains single mailboxes (Drafts, Trash, and others)
   ~/mail-Archives/ - This contains a hierarchy of folders containing 
mailboxes

   For example, a tree of ~/mail/ would look like this:
      ~/mail/
      ~/mail/Trash
      ~/mail/Drafts
      ~/mail/sent-mail
      ~/mail/My Stuff
      ~/mail/Important
      ~/mail/test/SomeFolder  <-- this would never happen, but I have to
                                  account for it during our transition

   A tree of ~/mail-Archives/ would look like this:
      ~mail-Archives/2009/MyStuff/MyStuff-Dec09
      ~mail-Archives/2009/MyStuff/MyStuff-Nov09
      ~mail-Archives/2009/MyStuff/MyStuff-Oct09
      ~mail-Archives/2010/MyStuff/MyStuff-Jan10
      ~mail-Archives/2010/Important/Important-Jan10

   All of that works, I can open up Thunderbird and browser/read/delete 
messages no problem.  However, when I try to move that 'test' folder 
from ~/mail/ into ~/mail-Archives I get an error message:

      'Can't rename mailbox to another storage type.'

   The same thing happens if I try to move any of the mailboxes in 
~/mail/ to ~/mail-Archives/ .  Is there a way to fix that?  Our 
namespaces look like this:


namespace private {
   separator = /
   prefix = "mail/"
   location = mbox:~/mail:INBOX=/var/mail/%u
   inbox = yes
   hidden = no
   list = yes   # for v1.1+
}

namespace private {
   separator = /
   prefix = "mail-Archives/"
   location = mbox:~/mail-Archives
   inbox = no
   hidden = no
   list = yes
   subscriptions = yes
}