[Dovecot] Unknown setting: dbox_attachment_dir

[imap at tnde.org]

Hi, I am trying to set up Dovecot with sdbox and sis (single instance
storage of attachments), however I get the following error when attempting
to start dovecot:

Starting Dovecot Imap: doveconf: Fatal: Error in configuration file
/etc/dovecot/dovecot.conf line 89: Unknown setting: dbox_attachment_dir

I'd appreciate help on getting this up and running. This is a virtual (for
the time being) server, running Centos, and Dovecot 2.

[root at localhost ~]# dovecot --build-options
Build options: ioloop=epoll notify=inotify ipv6 openssl io_block_size=8192
Mail storages: cydir maildir mbox mdbox raw sdbox shared
SQL driver plugins: mysql postgresql sqlite
Passdb: checkpassword ldap pam passwd passwd-file shadow sql
Userdb: checkpassword ldap(plugin) nss passwd prefetch passwd-file sql


[root at localhost ~]# dovecot -n
# 2.0.13: /etc/dovecot/dovecot.conf
# OS: Linux 2.6.18-238.9.1.el5 x86_64 CentOS release 5.6 (Final)
auth_debug = yes
auth_debug_passwords = yes
auth_verbose = yes
disable_plaintext_auth = no
mail_location = sdbox:~/dbox
mbox_write_locks = fcntl
passdb {
  driver = pam
}
ssl_cert = </etc/pki/dovecot/certs/dovecot.pem
ssl_key = </etc/pki/dovecot/private/dovecot.pem
userdb {
  driver = passwd
}