You may need to open the LDAP port on your Zimbra server:

# iptables -A INPUT -p tcp -m state --state NEW -m tcp --dport 389 -j ACCEPT

Determine your Zimbra LDAP password:

# su - zimbra
$ $ zmlocalconfig -s zimbra_ldap_password
zimbra_ldap_password = XXXXXXXXXXXX

Open the Barracuda Spam Firewall administration interface. Click the Domains tab. Click the Modify link next to the domain(s) you would like to enable bad recipient rejection for. Click on the LDAP Configuration sub-tab under the Users tab. Retain all defaults except:

• LDAP Server - Change this to the host name of your Zimbra server
• Bind DN (Username) - Change this to uid=zimbra,cn=admins,cn=zimbra
• Bind Password - Change this to your zimbra_ldap_password