IMAP folder separator issue

[Alex]

Hi,

I'm using dovecot-2.2.18 on fedora22 and having a problem with
Thunderbird. I reported this problem some time ago, and received some
tips, but no solution that's worked. I'm now trying to fix this in
earnest, and having problems.

The problem is sub-folders are created with a caret in them, instead
of a new folder below the parent folder. So instead of
folder/sub-folder, folder^sub-folder is created.

I'm using mbox folders, and it worked under previous versions of
fedora and dovecot. I believe it has to do with the separator
character that's used, based on this wiki page:

http://wiki2.dovecot.org/Plugins/Listescape

The problem is that those instructions cause errors:

Aug 14 20:00:01 orion dovecot: pop3(cerberus): Error: User
initialization failed: namespace configuration error: Duplicate
namespace prefix: ""
Aug 14 20:00:01 orion dovecot: pop3(cerberus): Error: Invalid user
settings. Refer to server log for more information.

I've also had to change the "namespace private" to "namespace {
type=private }" as that's apparently a deprecated syntax. Perhaps
there's an updated page with more instruction and correct information?

I'm unsure where this duplicate namespace is that it's talking about...

I've included my doveconf output below, in hopes someone can help. I
should also point out that "separator = $" is quoted in the original
doveconf.conf but apparently doveconf doesn't properly print it.

# 2.2.18: /etc/dovecot/dovecot.conf
# OS: Linux 4.0.7-300.fc22.x86_64 x86_64 Fedora release 22 (Twenty Two)
default_client_limit = 2000
mail_gid = mail
mail_location = mbox:~/mail:INBOX=/var/spool/mail/%u
mail_plugins = " listescape"
mail_privileged_group = mail
mbox_write_locks = fcntl
namespace {
  inbox = yes
  location =
  prefix =
  separator = $
  type = private
}
namespace inbox {
  inbox = yes
  location =
  mailbox Drafts {
    special_use = \Drafts
  }
  mailbox Junk {
    special_use = \Junk
  }
  mailbox Sent {
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Trash {
    special_use = \Trash
  }
  prefix =
}
passdb {
  driver = pam
}
passdb {
  driver = pam
}
protocols = imap pop3
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0660
    user = postfix
  }
}
service imap-login {
  inet_listener imap {
    port = 0
  }
  inet_listener imaps {
    port = 993
  }
  process_min_avail = 20
  service_count = 0
}
service pop3-login {
  inet_listener pop3 {
    port = 0
  }
  inet_listener pop3s {
    address = 192.168.1.100
    port = 995
  }
}
ssl_ca = </etc/pki/dovecot/certs/ca-bundle.pem
ssl_cert = </etc/pki/dovecot/certs/orion-2015.pem
ssl_key = </etc/pki/dovecot/certs/orion-2015.key
userdb {
  driver = passwd
}
userdb {
  driver = passwd
}