diff --git a/plugins/calendar/drivers/kolab/kolab_driver.php b/plugins/calendar/drivers/kolab/kolab_driver.php
index f921b530..90ea0844 100644
--- a/plugins/calendar/drivers/kolab/kolab_driver.php
+++ b/plugins/calendar/drivers/kolab/kolab_driver.php
@@ -1359,9 +1359,9 @@ class kolab_driver extends calendar_driver
       return false;
     }
 
-    list($uid, $folder) = $this->_resolve_event_identity($event);
+    list($uid, $mailbox) = $this->_resolve_event_identity($event);
 
-    $result = $this->bonnie_api->changelog('event', $uid, $folder);
+    $result = $this->bonnie_api->changelog('event', $uid, $mailbox);
     if (is_array($result) && $result['uid'] == $uid) {
       return $result['changes'];
     }
@@ -1384,10 +1384,10 @@ class kolab_driver extends calendar_driver
       return false;
     }
 
-    list($uid, $folder) = $this->_resolve_event_identity($event);
+    list($uid, $mailbox) = $this->_resolve_event_identity($event);
 
     // call Bonnie API
-    $result = $this->bonnie_api->diff('event', $uid, $rev, $folder);
+    $result = $this->bonnie_api->diff('event', $uid, $rev, $mailbox);
     if (is_array($result) && $result['uid'] == $uid) {
       $result['rev'] = $rev;
 
@@ -1502,23 +1502,17 @@ class kolab_driver extends calendar_driver
     }
 
     $calid = $event['calendar'];
-    list($uid, $folder) = $this->_resolve_event_identity($event);
+    list($uid, $mailbox) = $this->_resolve_event_identity($event);
 
     // call Bonnie API
-    $result = $this->bonnie_api->get('event', $uid, $rev, $folder);
+    $result = $this->bonnie_api->get('event', $uid, $rev, $mailbox);
     if (is_array($result) && $result['uid'] == $uid && !empty($result['xml'])) {
       $format = kolab_format::factory('event');
       $format->load($result['xml']);
       $event = $format->to_array();
 
       if ($format->is_valid()) {
-        if ($result['folder'] && ($cal = $this->get_calendar(kolab_storage::id_encode($result['folder'])))) {
-          $event['calendar'] = $cal->id;
-        }
-        else {
-          $event['calendar'] = $calid;
-        }
-
+        $event['calendar'] = $calid;
         $event['rev'] = $result['rev'];
         return self::to_rcube_event($event);
       }
@@ -1534,11 +1528,11 @@ class kolab_driver extends calendar_driver
    */
   private function _resolve_event_identity($event)
   {
-    $folder = null;
+    $mailbox = null;
     if (is_array($event)) {
       $uid = $event['id'] ?: $event['uid'];
-      if ($cal = $this->get_calendar($event['calendar']) && !($cal instanceof kolab_invitation_calendar)) {
-        $folder = $cal->name;
+      if (($cal = $this->get_calendar($event['calendar'])) && !($cal instanceof kolab_invitation_calendar)) {
+        $mailbox = $cal->get_mailbox_id();
       }
     }
     else {
@@ -1550,7 +1544,7 @@ class kolab_driver extends calendar_driver
     if (!in_array($uid, $demo_uids))
       $uid = reset($demo_uids);
 
-    return array($uid, $folder);
+    return array($uid, $mailbox);
   }
 
   /**
diff --git a/plugins/calendar/drivers/kolab/kolab_invitation_calendar.php b/plugins/calendar/drivers/kolab/kolab_invitation_calendar.php
index ac3740a7..24fad592 100644
--- a/plugins/calendar/drivers/kolab/kolab_invitation_calendar.php
+++ b/plugins/calendar/drivers/kolab/kolab_invitation_calendar.php
@@ -114,6 +114,17 @@ class kolab_invitation_calendar
     return $this->get_name();
   }
 
+  /**
+   * Getter for the Cyrus mailbox identifier corresponding to this folder
+   *
+   * @return string Mailbox ID
+   */
+  public function get_mailbox_id()
+  {
+    // this is a virtual collection and has no concrete mailbox ID
+    return null;
+  }
+
   /**
    * Return color to display this calendar
    */
diff --git a/plugins/libkolab/lib/kolab_bonnie_api.php b/plugins/libkolab/lib/kolab_bonnie_api.php
index 732d29b5..23dafd82 100644
--- a/plugins/libkolab/lib/kolab_bonnie_api.php
+++ b/plugins/libkolab/lib/kolab_bonnie_api.php
@@ -50,25 +50,25 @@ class kolab_bonnie_api
     /**
      * Wrapper function for <object>.changelog() API call
      */
-    public function changelog($type, $uid, $folder=null)
+    public function changelog($type, $uid, $mailbox=null)
     {
-        return $this->client->execute($type.'.changelog', array('uid' => $uid, 'folder' => $folder));
+        return $this->client->execute($type.'.changelog', array('uid' => $uid, 'mailbox' => $mailbox));
     }
 
     /**
      * Wrapper function for <object>.diff() API call
      */
-    public function diff($type, $uid, $rev, $folder=null)
+    public function diff($type, $uid, $rev, $mailbox=null)
     {
-        return $this->client->execute($type.'.diff', array('uid' => $uid, 'rev' => $rev, 'folder' => $folder));
+        return $this->client->execute($type.'.diff', array('uid' => $uid, 'rev' => $rev, 'mailbox' => $mailbox));
     }
 
     /**
      * Wrapper function for <object>.get() API call
      */
-    public function get($type, $uid, $rev, $folder=null)
+    public function get($type, $uid, $rev, $mailbox=null)
     {
-      return $this->client->execute($type.'.get', array('uid' => $uid, 'rev' => intval($rev), 'folder' => $folder));
+      return $this->client->execute($type.'.get', array('uid' => $uid, 'rev' => intval($rev), 'mailbox' => $mailbox));
     }
 
     /**
diff --git a/plugins/libkolab/lib/kolab_storage_folder_api.php b/plugins/libkolab/lib/kolab_storage_folder_api.php
index 4a904671..ef3309e0 100644
--- a/plugins/libkolab/lib/kolab_storage_folder_api.php
+++ b/plugins/libkolab/lib/kolab_storage_folder_api.php
@@ -167,6 +167,38 @@ abstract class kolab_storage_folder_api
         return join('/', $path);
     }
 
+    /**
+     * Getter for the Cyrus mailbox identifier corresponding to this folder
+     * (e.g. user/john.doe/Calendar/Personal@example.org)
+     *
+     * @return string Mailbox ID
+     */
+    public function get_mailbox_id()
+    {
+        $info = $this->get_folder_info();
+        $owner = $this->get_owner();
+        list($user, $domain) = explode('@', $owner);
+
+        switch ($info['namespace']) {
+        case 'personal':
+            return sprintf('user/%s/%s@%s', $user, $this->name, $domain);
+
+        case 'shared':
+            $ns = $this->imap->get_namespace('shared');
+            $prefix = is_array($ns) ? $ns[0][0] : '';
+            list(, $domain) = explode('@', rcube::get_instance()->get_user_name());
+            return substr($this->name, strlen($prefix)) . '@' . $domain;
+
+        default:
+            $ns = $this->imap->get_namespace('other');
+            $prefix = is_array($ns) ? $ns[0][0] : '';
+            list($user, $folder) = explode($this->imap->get_hierarchy_delimiter(), substr($info['name'], strlen($prefix)), 2);
+            if (strpos($user, '@')) {
+                list($user, $domain) = explode('@', $user);
+            }
+            return sprintf('user/%s/%s@%s', $user, $folder, $domain);
+        }
+    }
 
     /**
      * Get the color value stored in metadata