diff --git a/plugins/kolab_auth/kolab_auth.php b/plugins/kolab_auth/kolab_auth.php
index 79b10183..ad380225 100644
--- a/plugins/kolab_auth/kolab_auth.php
+++ b/plugins/kolab_auth/kolab_auth.php
@@ -31,6 +31,7 @@
 class kolab_auth extends rcube_plugin
 {
     static $ldap;
+    private $username;
     private $data = array();
 
     public function init()
@@ -56,11 +57,13 @@ class kolab_auth extends rcube_plugin
         // Hook to modify some configuration, e.g. ldap
         $this->add_hook('config_get', array($this, 'config_get'));
 
+        // Hook to modify logging directory
+        $this->add_hook('write_log', array($this, 'write_log'));
+        $this->username = $_SESSION['username'];
+
         // Enable debug logs per-user, this enables logging only after
         // user has logged in
         if (!empty($_SESSION['username']) && $rcmail->config->get('kolab_auth_auditlog')) {
-            $this->add_hook('write_log', array($this, 'write_log'));
-
             $rcmail->config->set('debug_level', 1);
             $rcmail->config->set('devel_mode', true);
             $rcmail->config->set('smtp_log', true);
@@ -241,37 +244,29 @@ class kolab_auth extends rcube_plugin
             return $args;
         }
 
-        $line = sprintf("[%s]: %s\n", $args['date'], $args['line']);
-
         // log_driver == 'file' is assumed here
         $log_dir  = $rcmail->config->get('log_dir', RCUBE_INSTALL_PATH . 'logs');
-        $log_path = $log_dir.'/'.strtolower($_SESSION['kolab_auth_admin']).'/'.strtolower($_SESSION['username']);
 
-        // Append original username + target username
-        if (!is_dir($log_path)) {
+        // Append original username + target username for audit-logging
+        if ($rcmail->config->get('kolab_auth_auditlog') && !empty($_SESSION['kolab_auth_admin'])) {
+            $args['dir'] = $log_dir . '/' . strtolower($_SESSION['kolab_auth_admin']) . '/' . strtolower($this->username);
+
             // Attempt to create the directory
-            if (@mkdir($log_path, 0750, true)) {
-                $log_dir = $log_path;
+            if (!is_dir($args['dir'])) {
+                @mkdir($args['dir'], 0750, true);
             }
         }
-        else {
-            $log_dir = $log_path;
+        // Define the user log directory if a username is provided
+        else if ($rcmail->config->get('per_user_logging') && !empty($this->username)) {
+            $user_log_dir = $log_dir . '/' . strtolower($this->username);
+            if (is_writable($user_log_dir)) {
+                $args['dir'] = $user_log_dir;
+            }
+            else if ($args['name'] != 'errors') {
+                $args['abort'] = true;  // don't log if unauthenticed
+            }
         }
 
-        // try to open specific log file for writing
-        $logfile = $log_dir.'/'.$args['name'];
-
-        if ($fp = fopen($logfile, 'a')) {
-            fwrite($fp, $line);
-            fflush($fp);
-            fclose($fp);
-        }
-        else {
-            trigger_error("Error writing to log file $logfile; Please check permissions", E_USER_WARNING);
-        }
-
-        $args['abort'] = true;
-
         return $args;
     }
 
@@ -353,6 +348,9 @@ class kolab_auth extends rcube_plugin
             return $args;
         }
 
+        // temporarily set the current username to the one submitted
+        $this->username = $user;
+
         $ldap = self::ldap();
         if (!$ldap || !$ldap->ready) {
             $args['abort'] = true;
@@ -483,7 +481,7 @@ class kolab_auth extends rcube_plugin
                 return $args;
             }
 
-            $args['user'] = $loginas;
+            $args['user'] = $this->username = $loginas;
 
             // Mark session to use SASL proxy for IMAP authentication
             $_SESSION['kolab_auth_admin']    = strtolower($origname);
@@ -506,7 +504,7 @@ class kolab_auth extends rcube_plugin
             $this->data['user_login'] = is_array($record[$login_attr]) ? $record[$login_attr][0] : $record[$login_attr];
         }
         if ($this->data['user_login']) {
-            $args['user'] = $this->data['user_login'];
+            $args['user'] = $this->username = $this->data['user_login'];
         }
 
         // User name for identity (first log in)