I tried it with your hint, but it still does not work:
$rcmail_config['ldap_public']['freeldap'] = array(
'name' => 'freeldap',
'hosts' => array('ds1.us.freeldap.org'),
'port' => 389,
'base_dn' => 'uid=Vicelow, ou=People, o=entic.net',
'bind_dn' => 'uid=Vicelow, ou=People, o=entic.net',
'bind_pass' => 'mypassword',
'ldap_version' => 3, // using LDAPv3
'search_fields' => array('mail', 'cn'), // fields to search in
'name_field' => 'cn', // this field represents the contact's name
'email_field' => 'mail', // this field represents the contact's e-mail
'surname_field' => 'sn', // this field represents the contact's last name
'firstname_field' => 'gn', // this field represents the contact's first name
'scope' => 'sub', // search mode: sub|base|list
'filter' => '', // used for basic listing (if not empty) and will be &'d with search queries. example: status=act
'fuzzy_search' => true); // server allows wildcard search
Still it does not match any freelap entries though it finds them in the addressbook.
Any idea?