debug configOptions

zimbraSingle.inc

@@ -410,6 +410,7 @@ function zimbraSingleConfigOptions($params) {
     $configOptions['maildomains'] = array(
         "FriendlyName" => "Mail Domain",
         "Type" => "dropdown",
+        "Multiple" => true,
         "Options" => implode(',', $domainNames),
         "Description" => "select maildomains",
     );