This is what I've done. Seems to work. Hope it helps someone without crashing everything. Debian stretch standard package.

/usr/share/roundcube/plugins/new_user_identity/new_user_identity.php.orig 2018-10-03 09:40:46.814463985 +0200 +++ /usr/share/roundcube/plugins/new_user_identity/new_user_identity.php 2018-10-04 15:08:42.176370477 +0200 @@ -33,8 +33,10 @@              if (count($results->records) == 1) {                  $user_name  = is_array($results->records[0]['name']) ? $results->records[0]['name'][0] : $results->records[0]['name'];                  $user_email = is_array($results->records[0]['email']) ? $results->records[0]['email'][0] : $results->records[0]['email']; +                $user_org = is_array($results->records[0]['organization']) ? $results->records[0]['organization'][0] : $results->records[0]['organization'];

$args['user_name']  = $user_name; +                $args['user_org']  = $user_org;                  $args['email_list'] = array();

if (!$args['user_email'] && strpos($user_email, '@')) { @@ -70,9 +72,8 @@          $identities = $this->rc->user->list_emails();          $ldap_entry = $this->lookup_user_name(array(                  'user' => $this->rc->user->data['username'], -                'host' => $this->rc->user->data['mail_host'], +                'host' => $this->rc->user->data['mail_host']          ));

foreach ((array) $ldap_entry['email_list'] as $email) {              foreach ($identities as $identity) {                  if ($identity['email'] == $email) {

--- /usr/share/roundcube/program/lib/Roundcube/rcube_user.php.orig 2016-11-27 18:08:58.000000000 +0200 +++ /usr/share/roundcube/program/lib/Roundcube/rcube_user.php 2018-10-04 15:17:32.542990608 +0200 @@ -630,7 +630,7 @@              $user_name   = $data['user_name'];              $user_email  = $data['user_email'];              $email_list  = $data['email_list'];

+            $user_org  = $data['user_org'];              if (empty($email_list)) {                  if (empty($user_email)) {                      $user_email = strpos($data['user'], '@') ? $user : sprintf('%s@%s', $data['user'], $mail_domain); @@ -667,6 +667,7 @@

$record['user_id']  = $user_id;                  $record['standard'] = $standard; +                $record['organization'] = $user_org;

$plugin = $rcube->plugins->exec_hook('identity_create',                      array('login' => true, 'record' => $record));