diff --git a/plugins/libkolab/SQL/mysql/2014112700.sql b/plugins/libkolab/SQL/mysql/2014112700.sql
new file mode 100644
index 00000000..90c77b85
--- /dev/null
+++ b/plugins/libkolab/SQL/mysql/2014112700.sql
@@ -0,0 +1,2 @@
+-- delete cache entries for old folder identifiers
+DELETE FROM `kolab_folders` WHERE `resource` LIKE 'imap://anonymous@%';
diff --git a/plugins/libkolab/lib/kolab_storage_folder.php b/plugins/libkolab/lib/kolab_storage_folder.php
index d33f9d07..d6d17c82 100644
--- a/plugins/libkolab/lib/kolab_storage_folder.php
+++ b/plugins/libkolab/lib/kolab_storage_folder.php
@@ -97,7 +97,7 @@ class kolab_storage_folder extends kolab_storage_folder_api
         }
 
         // compose fully qualified ressource uri for this instance
-        $this->resource_uri = 'imap://' . urlencode($this->get_owner()) . '@' . $this->imap->options['host'] . '/' . $subpath;
+        $this->resource_uri = 'imap://' . urlencode($this->get_owner(true)) . '@' . $this->imap->options['host'] . '/' . $subpath;
         return $this->resource_uri;
     }
 
diff --git a/plugins/libkolab/lib/kolab_storage_folder_api.php b/plugins/libkolab/lib/kolab_storage_folder_api.php
index ea603b1b..7280389e 100644
--- a/plugins/libkolab/lib/kolab_storage_folder_api.php
+++ b/plugins/libkolab/lib/kolab_storage_folder_api.php
@@ -85,9 +85,10 @@ abstract class kolab_storage_folder_api
     /**
      * Returns the owner of the folder.
      *
+     * @param boolean  Return a fully qualified owner name (i.e. including domain for shared folders)
      * @return string  The owner of this folder.
      */
-    public function get_owner()
+    public function get_owner($fully_qualified = false)
     {
         // return cached value
         if (isset($this->owner))
@@ -106,16 +107,21 @@ abstract class kolab_storage_folder_api
             break;
 
         default:
-            list($prefix, $user) = explode($this->imap->get_hierarchy_delimiter(), $info['name']);
-            if (strpos($user, '@') === false) {
-                $domain = strstr($rcmail->get_user_name(), '@');
-                if (!empty($domain))
-                    $user .= $domain;
-            }
-            $this->owner = $user;
+            list($prefix, $this->owner) = explode($this->imap->get_hierarchy_delimiter(), $info['name']);
+            $fully_qualified = true;  // enforce email addresses (backwards compatibility)
             break;
         }
 
+        if ($fully_qualified && strpos($this->owner, '@') === false) {
+            // extract domain from current user name
+            $domain = strstr($rcmail->get_user_name(), '@');
+            // fall back to mail_domain config option
+            if (empty($domain) && ($mdomain = $rcmail->config->mail_domain($this->imap->options['host']))) {
+                $domain = '@' . $mdomain;
+            }
+            $this->owner .= $domain;
+        }
+
         return $this->owner;
     }