Sorry, forgot to mention that some of my users indeed have more than 
one email address, so i properly use: "emails" instead of "email".

Request 11032.

The contact autocompleter doesn't work under IMP, altought it's 
working in other applications (like kronolith) and the Addressbooks 
work fine when directly searched with turba.

Relevant configurations:

turba backends.local.php (obscured LDAP details and password)

<?php
$cfgSources['localldap'] = array(
      'disabled' => false,
      'title' => _("GAL"),
      'type' => 'ldap',
      'params' => array(
         'server' => 'ldaps://ldap.example.net',
         'port' => 686,
         'tls' => false,
         'root' => 'ou=users,dc=example,dc=net',
         'bind_dn' => 'uid=gal,ou=replicas,dc=example,dc=net',
         'bind_password' => '*********',
         'sizelimit' => 200,
         'dn' => array('cn'),
         'objectclass' => array('calEntry',
                                'inetOrgPerson'),
         'scope' => 'sub',
         'charset' => 'utf-8',
         'checkrequired' => false,
         'checkrequired_string' => ' ',
         'checksyntax' => false,
         'version' => 3,
      ),
      'map' => array(
         '__key' => 'dn',
         '__uid' => 'uid',
         'firstname' => 'givenName',
         'lastname' => 'sn',
         /*      'name' => 'cn', */
         'name' => array('fields' => array('firstname','lastname'),
                                 'format' => '%s %s',
                                 'parse' => array(
                                     array('fields' => 
array('firstname','lastname'),
                                     'format' => '%s %s'))),
         'emails' => 'mail',
         'workPhone' => 'telephonenumber',
         'cellPhone' => 'mobile',
         'freebusyUrl' => 'calFBURL',
         'employeeNumber' => 'employeeNumber',
      ),
      'search' => array(
         'name',
         'emails',
      ),
      'strict' => array(
        'dn',
      ),
      'approximate' => array(
         'cn',
         'sn',
         'uid',
      ),
      'export' => true,
      'browse' => true,
);

$cfgSources['localsql'] = array(
     // ENABLED by default
     'disabled' => false,
     'title' => _("Personal Addressbook"),
     'type' => 'sql',
     'params' => array_merge($GLOBALS['conf']['sql'], array('table' => 
'turba_objects')),
     'map' => array(
         '__key' => 'object_id',
         '__owner' => 'owner_id',
/*      '__type' => 'object_type',
         '__members' => 'object_members',
         '__uid' => 'object_uid',*/
         'firstname' => 'object_firstname',
         'lastname' => 'object_lastname',
         'middlenames' => 'object_middlenames',
/*      'namePrefix' => 'object_nameprefix',
         'nameSuffix' => 'object_namesuffix',
         'name' => array('fields' => array('namePrefix', 'firstname',
                                           'middlenames', 'lastname',
                                           'nameSuffix'),
                         'format' => '%s %s %s %s %s',
                         'parse' => array(
                             array('fields' => array('firstname', 
'middlenames',
                                                     'lastname'),
                                   'format' => '%s %s %s'),
                             array('fields' => array('firstname', 'lastname'),
                             'format' => '%s %s'))),*/
         // This is a shorter version of a "name" composite field which only
         // consists of the first name and last name.
         'name' => array('fields' => array('firstname', 'lastname'),
                          'format' => '%s %s'),
/*      'alias' => 'object_alias',
         'birthday' => 'object_bday',
         'anniversary' => 'object_anniversary',
         'spouse' => 'object_spouse',
         'photo' => 'object_photo',
         'phototype' => 'object_phototype',
         'homeStreet' => 'object_homestreet',
         'homePOBox' => 'object_homepob',
         'homeCity' => 'object_homecity',
         'homeProvince' => 'object_homeprovince',
         'homePostalCode' => 'object_homepostalcode',
         'homeCountry' => 'object_homecountry',
         'homeAddress' => array('fields' => array('homeStreet', 'homeCity',
                                                  'homeProvince',
                                                  'homePostalCode'),
                                'format' => "%s \n %s, %s  %s"),
         'workStreet' => 'object_workstreet',
         'workPOBox' => 'object_workpob',
         'workCity' => 'object_workcity',
         'workProvince' => 'object_workprovince',
         'workPostalCode' => 'object_workpostalcode',
         'workCountry' => 'object_workcountry',
         'workAddress' => array('fields' => array('workStreet', 'workCity',
                                                  'workProvince',
                                                  'workPostalCode'),
                                'format' => "%s \n %s, %s  %s"),
         'department' => 'object_department',
         'timezone' => 'object_tz',*/
         'email' => 'object_email',
/*      'homePhone' => 'object_homephone',
         'homeFax' => 'object_homefax',*/
         'workPhone' => 'object_workphone',
/*      'cellPhone' => 'object_cellphone',
         'assistPhone' => 'object_assistantphone',
         'fax' => 'object_fax',
         'pager' => 'object_pager',
         'title' => 'object_title',
         'role' => 'object_role',
         'company' => 'object_company',
         'logo' => 'object_logo',
         'logotype' => 'object_logotype',
         'category' => 'object_category',
         'notes' => 'object_notes',
         'website' => 'object_url',
         'freebusyUrl' => 'object_freebusyurl',
         'pgpPublicKey' => 'object_pgppublickey',
         'smimePublicKey' => 'object_smimepublickey',
         'imaddress' => 'object_imaddress',
         'imaddress2' => 'object_imaddress2',
         'imaddress3' => 'object_imaddress3' */
     ),
     'tabs' => array(
         _("Personal") => array('firstname', 'lastname', 'middlenames',
                                'namePrefix', 'nameSuffix', 'name', 'alias',
                                'birthday', 'spouse', 'anniversary', 'photo'),
         _("Location") => array('homeStreet', 'homePOBox', 'homeCity',
                                'homeProvince', 'homePostalCode', 
'homeCountry',
                                'homeAddress', 'workStreet', 'workPOBox',
                                'workCity', 'workProvince', 'workPostalCode',
                                'workCountry', 'workAddress', 'timezone'),
         _("Communications") => array('email', 'homePhone', 'workPhone',
                                      'assistPhone', 'homeFax',
                                      'cellPhone', 'fax', 'pager', 'imaddress',
                                      'imaddress2', 'imaddress3'),
         _("Organization") => array('title', 'role', 'company', 
'department', 'logo'),
         _("Other") => array('category', 'notes', 'website', 'freebusyUrl',
                             'pgpPublicKey', 'smimePublicKey'),
     ),
     'search' => array(
         'name',
         'email'
     ),
/*    'strict' => array(
         'object_id',
         'owner_id',
         'object_type',
),*/
     'export' => true,
     'browse' => true,
     'use_shares' => true,
     'list_name_field' => 'lastname',
     'alternative_name' => 'company',
);

Turba conf.php

$conf['menu']['import_export'] = true;
$conf['menu']['apps'] = array();
$conf['client']['addressbook'] = 'localsql';
$conf['gal']['addressbook'] = 'localldap';
$conf['shares']['source'] = '\'\'';
$conf['comments']['allow'] = true;
$conf['documents']['type'] = 'horde';

IMP conf.php
$conf['user']['autocreate_special'] = false;
$conf['user']['select_sentmail_folder'] = false;
$conf['user']['allow_folders'] = true;
$conf['user']['allow_view_source'] = true;
$conf['server']['server_list'] = 'none';
$conf['server']['fixed_folders'] = array();
$conf['msgsettings']['filtering']['words'] = './config/filter.txt';
$conf['msgsettings']['filtering']['replacement'] = '****';
$conf['spam']['reporting'] = false;
$conf['notspam']['reporting'] = false;
$conf['print']['add_printedby'] = false;
$conf['compose']['use_vfs'] = false;
$conf['compose']['link_attachments'] = false;
$conf['compose']['attach_size_limit'] = 0;
$conf['compose']['attach_count_limit'] = 0;
$conf['compose']['convert_to_related'] = true;
$conf['compose']['reply_limit'] = 200000;
$conf['compose']['ac_browser'] = 50;
$conf['compose']['ac_threshold'] = 3;
$conf['maillog']['use_maillog'] = true;
$conf['sentmail']['params']['threshold'] = 60;
$conf['sentmail']['params']['limit_period'] = 24;
$conf['sentmail']['params']['table'] = 'imp_sentmail';
$conf['sentmail']['params']['driverconfig'] = 'horde';
$conf['sentmail']['driver'] = 'Sql';
$conf['tasklist']['use_tasklist'] = true;
$conf['notepad']['use_notepad'] = true;
$conf['dimp']['viewport']['buffer_pages'] = 10;
$conf['dimp']['viewport']['viewport_wait'] = 10;
$conf['menu']['apps'] = array('ingo', 'kronolith', 'mnemo', 'turba');
$conf['menu']['apps_iframe'] = false;

With these configs as i noted before, it's possible to autocomplete 
and search in other apps. IMP however it's uncapable of doing so. 
(i've even tested a new user without any specific preferences set)

Could you help me track down the issue?

Kind regards.