Hi Altangerel, we're using MS ADS (Windows 2003 servers) as LDAP backend for OTRS very successfully. I'm sending the appropriate section of our configuration, which we haven't have any problems yet with, like you described. $Self->{CustomerUser} = { Name => 'LDAP Backend', Module => 'Kernel::System::CustomerUser::LDAP', Params => { Host => 'mdname.firma.com', BaseDN => 'dc=firma,dc=com', SSCOPE => 'sub', UserDN => 'domain\username', UserPw => 'userpass', AlwaysFilter => '(objectclass=user)', Die => 1, Params => { raw => qr/(?i:^jpegPhoto|;binary)/, }, }, CustomerKey => 'cn', CustomerID => 'mail', CustomerUserListFields => ['cn', 'mail'], CustomerUserSearchFields => ['cn', 'sn', 'mail'], CustomerUserPostMasterSearchFields => ['mail', 'cn', 'sn'], CustomerUserNameFields => ['givenname', 'sn'], Map => [ [ 'UserSalutation', 'Title', 'title', 1, 0, 'var', '', 0 ], [ 'UserFirstname', 'Firstname', 'givenname', 1, 1, 'var', '', 0 ], [ 'UserLastname', 'Lastname', 'sn', 1, 1, 'var', '', 0 ], [ 'UserLogin', 'Login', 'cn', 1, 1, 'var', '', 0 ], [ 'UserEmail', 'Email', 'mail', 1, 1, 'var', '', 0 ], [ 'UserCustomerID', 'CustomerID', 'mail', 0, 1, 'var', '', 0 ], [ 'UserPhone', 'Phone', 'telephonenumber', 1, 0, 'var', '', 0 ], [ 'UserAddress', 'Address', 'postaladdress', 1, 0, 'var', '', 0 ], [ 'UserComment', 'Comment', 'description', 1, 0, 'var', '', 0 ], [ 'UserLocation', 'Location', 'l', 1, 0, 'var', '', 0 ], ], }; Have you already searched with ldapsearch? Have you seen any differences between the data of users, who can be found and who cannot? Which perl-ldap package are you using? We're using 0.34. Mit freundlichen Grüßen / Kind Regards Hermann Maurer