[Dovecot] quota exceeded not showing email address

[JC]

Hi everyone,
I have a mail server with postfix 2.3.8-2, dovecot 1.0.0 and mysql with virtual
users and domains. Everything is working but when a mail bounces it doesn't show
me what is the email address with overquota. 
I'm using Dovecot Delivery Agent to send a mail when an email bounces. 
This is the message that shows me:
Your message was automatically rejected by Dovecot Mail Delivery Agent.
The following reason was given:
Quota exceeded

It doesn't show me what is the email address.

In my /etc/postfix/master.cf I added this:
dovecot   unix  -       n       n       -       -       pipe
  flags=DRhu user=xyz:xyz argv=/usr/lib/dovecot/deliver -d ${recipient}

In my /etc/postfix/main.cf I added this:
dovecot_destination_recipient_limit = 1
virtual_transport = dovecot

In my /etc/dovecot/dovecot.conf :
protocol lda {
    postmaster_address = <postmaster-address>
    auth_socket_path = /var/run/dovecot/auth-master
  }
...
user = xyz
socket listen {
    master {
      path = /var/run/dovecot/auth-master
      mode = 0660
      user = xyz
      group = xyz
    }
  }

What should i have to show the email address?