[Dovecot] Public maiboxes

[bonnetf]

hello

I'm trying to setup a server with public mailboxes only
but I cannot succeed.
Anyone could help me a bit ? thank you

here is the doveconf -n output

# 2.1.6: /usr/local/etc/dovecot/dovecot.conf
# OS: FreeBSD 7.4-RELEASE-p3 amd64
auth_debug = yes
debug_log_path = /var/log/dovecot/debug.log
disable_plaintext_auth = no
info_log_path = /var/log/dovecot/info.log
log_path = /var/log/dovecot/dovecot.log
mail_debug = yes
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope 
encoded-character vacation subaddress comparator-i;ascii-numeric 
relational regex imap4flags copy include variables body enotify 
environment mailbox date ihave
namespace {
  list = children
  location = maildir:/var/mail/public
  prefix = public.
  separator = /
  subscriptions = no
  type = public
}
namespace inbox {
  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 {
  args = /usr/local/etc/dovecot/dovecot-ldap.conf.ext
  driver = ldap
}
plugin {
  acl = vfile
  sieve = ~/.dovecot.sieve
  sieve_dir = ~/sieve
}
ssl_cert = </etc/ssl/RENATER/cert-2209-webmail.esiee.fr.pem
ssl_key = </etc/ssl/RENATER/webmail.esiee.fr.key
userdb {
  args = /usr/local/etc/dovecot/dovecot-ldap.conf.ext
  driver = ldap
}
protocol imap {
  mail_plugins = " imap_acl"
}