[Dovecot] virtual Folder Plugin with "." Separator: [NONEXISTENT] Mailbox doesn't exist

[Elmar Weber]

Hello,

I've switched from courier-imap to dovecot to benefit from the virtual
folder feature. I'm using dovecot 1.2.6 on Gentoo Linux. However, I',
getting the message "[NONEXISTENT] Mailbox doesn't exist: <name>" from
Thunderbird when I try to access any virtual folder.

The relevant setup:

mail_location = maildir:~/.maildir

namespace private {
    separator = .
    inbox = yes
    hidden = yes
    list = yes
}

namespace private {
   prefix = virtual.
   separator = .
   location = virtual:~/.maildir/.virtual
}

I then created the folders ~user/.maildir/.virtual and
~user/.maildir/.virtual.test and placed a file in .virtual.test with the
contents

======
*
   all
======

After a dovecot restart I'm getting the error message:
"[NONEXISTENT] Mailbox doesn't exist: test"

Where did I make the mistake in the configuration? Is the "." path
separator a problem case?

ciao,
Elmar