The Address Book Service

This feature, part of the Mobile module, provides an LDAP Address Book that Outlook clients can connect to in order to access the system’s GAL, the user’s own address books and other address books defined by the Administrator.

This service is the core of the LDAP Address Book feature, as it provides the endpoint to which the Outlook clients connect.

The service is exposed on port 8389 of all mailbox services and uses the TLS encryption protocol.

This endpoint is read-only, to improve the system’s security.

Accessing the LDAP Address Book

The LDAP Address Book can be only accessed by Outlook clients through the same credentials used for Exchange ActiveSync connection (email address and either their password or a dedicated Mobile Password.)

Clients can reach the service by contacting port 8389 of the mailbox server hosting their mailbox.


Since it is not possible to route requests through the NGINX web server installed on Carbonio, the connection must be established to the exact server and not the system’s general FQDN.

Another options would be to define custom firewall rules to forward port 8389 from the proxy to the AppServer, as explained in the procedure below, which requires to modify some system files and assumes the mailbox server is located at the local IP

  1. Enable IPv4 IP forwarding

  2. Add these firewall rules to the iptables script of your proxy:

    -t nat -A PREROUTING -p tcp --dport 8389 -j DNAT --to-destination
    -A FORWARD -p tcp --dport 8389 -m state --state -NEW,ESTABLISHED,RELATED -j ACCEPT


    The second rule is only needed if your default is rejected.

Contacts and Address Books

By default, the LDAP Address book provides access to the following items:

  • An user’s own address books and contacts.

  • The user’s GAL.

Other users’ address books, including shared ones, are not visible in the LDAP Address Book.

Additional Address Books

An Administrator can manage additional Address Books at domain and global levels through the carbonio mobile addressBook subcommands.

zextras$ carbonio mobile addressBook list

List all current Address Books exposed in the LDAP Address Book

zextras$ carbonio mobile addressBook add

Add a new Address Book to the LDAP Address Book

zextras$ carbonio mobile addressBook remove

Remove an Address Book from the LDAP Address Book

The first parameter of the add and remove sub-command is the scope to which the Address Book will be visible, either Global or Domain.

Moreover, both sub-commands also require the Address Book owner’s e-mail address or UUID and the FolderID of the address book being added.


zextras$ carbonio mobile addressBook add global 2

This command adds folder 2 (the default /Contacts folder) of the user to the LDAP Address Book of all users in the system.

zextras$ carbonio mobile addressBook add domain 2

This command adds folder 2 (the default /Contacts folder) of the user to the LDAP Address Book of all users in the domain.

Additional Address Books will be displayed in Outlook’s LDAP Search by showing the owner’s Display Name and the Address Book name separated by a slash, e.g. “John Doe/EMEA Distributors”.

Outlook setup

To access the LDAP Address Book from Outlook simply follow these steps:

  1. In the Account Settings section, enter the Address Books tab and click Add

  2. Select Internet Directory Service (LDAP) and press Next


    Fig. 5 First two steps of the procedure

  3. Enter the direct URL of the mailbox server, then tick the This server requires me to log in checkbox and enter your email address and password (or Mobile Password if existing)


    Fig. 6 URL and credentials setup

  4. Click More Settings

  5. In the Connection tab enter the server’s URL as the Display Name and 8389 as the port, then tick the Use Secure Socket Layer checkbox


    Fig. 7 Secure the connection

  6. In the Search tab, select Custom as the search base and leave the input field blank.


    Fig. 8 Set up LDAP search

  7. Click Ok to close the More Options window and Next on the Add Account window to conclude the process.

Address Book naming

In Outlook, own Address Books accessed by LDAP are named with a slash character preceding the name of the folder, e.g. “/Contacts”.

GAL entries and Address Books also include the name of the datasource, e.g. “InternalGAL/_zextras”.

Other users’ Address Books include the Display Name of the owner and the folder name, e.g. “John Doe/EMEA Partners”.