diff --git a/plugins/kolab_delegation/config.inc.php.dist b/plugins/kolab_delegation/config.inc.php.dist
index efa47e60..12e04d5b 100644
--- a/plugins/kolab_delegation/config.inc.php.dist
+++ b/plugins/kolab_delegation/config.inc.php.dist
@@ -2,7 +2,7 @@
 
 // This will overwrite defined LDAP filter
 // Note: LDAP addressbook defined for kolab_auth plugin is used
-$config['kolab_delegation_filter'] = '(objectClass=kolabInetOrgPerson)';
+$config['kolab_delegation_filter'] = '(|(objectClass=kolabInetOrgPerson)(&(objectclass=kolabsharedfolder)(kolabFolderType=mail)))';
 
 // Delegates field (from fieldmap configuration) to get delegates list
 // Note: This is a field name, not LDAP attribute name
diff --git a/plugins/kolab_delegation/kolab_delegation_engine.php b/plugins/kolab_delegation/kolab_delegation_engine.php
index be16cf69..88e4563b 100644
--- a/plugins/kolab_delegation/kolab_delegation_engine.php
+++ b/plugins/kolab_delegation/kolab_delegation_engine.php
@@ -223,7 +223,7 @@ class kolab_delegation_engine
         }
 
         // Default filter of LDAP queries
-        $this->ldap_filter = $this->rc->config->get('kolab_delegation_filter', '(objectClass=kolabInetOrgPerson)');
+        $this->ldap_filter = $this->rc->config->get('kolab_delegation_filter', '(|(objectClass=kolabInetOrgPerson)(&(objectclass=kolabsharedfolder)(kolabFolderType=mail)))');
         // Name of the LDAP field for delegates list
         $this->ldap_delegate_field = $this->rc->config->get('kolab_delegation_delegate_field', 'kolabDelegate');
         // Encoded LDAP DN of current user, set on login by kolab_auth plugin