[Dovecot] Configure replication in backup mode

[japerez]

Dovecot 2.2.27 (c0f36b0)

I'm trying to configure dovecot to backup all my email to a secondary 
server using "dsync".

I got it working in "sync" mode or two-way synchonization, that means 
whatever happens in one server gets replicated in the other.

However, documentation also says that a one way synchronization is 
posible, yet, after spending a good amount of hours searching,
I failed to find what do I have to modify in my "30-dsync.conf" to do 
so.

My 30-dsync.conf reads as follows:

#This sets globally the port needed to connect
#to the doveadm service
#doveadm_port = 12345

# Set the password globally to use for connecting to
# and requiring for the doveadm service
doveadm_password = +++++++++++++

# Set the directory for validating certificates
# provided when running with SSL enabled
# Should be the standard OpenSSL certificate directory by default
ssl_client_ca_dir = /etc/ssl/certs

# Configure the doveadm service to listen
service doveadm {
   inet_listener {
# port to listen on
       port = 12345
           # enable SSL
         #  ssl = yes
    }
}

# Configure the aggregator service for notifications
service aggregator {
   fifo_listener replication-notify-fifo {
# Your mail user that's managing files generally is used here
       user = +++++
       mode = 0755
    }
    unix_listener replication-notify {
      user = +++++
      mode = 0755
    }
}

# Configure the replicator service
service replicator {
   user = root
   process_min_avail = 1
     unix_listener replicator-doveadm {
       user = root
       mode = 0755
     }
}

replication_dsync_parameters = -d -N -l 30 -U -x nobody
# Configure target hosts for replication
# tcps can be tcp if you don't want to connect with SSL
# :port can be omitted if it's the default set globally for doveadm
plugin {
   mail_replica = tcp:*.*.*.*:12345
}

Thanks.