diff --git a/core/admin/mailu/ui/forms.py b/core/admin/mailu/ui/forms.py
index 959f46b2..c6335559 100644
--- a/core/admin/mailu/ui/forms.py
+++ b/core/admin/mailu/ui/forms.py
@@ -47,7 +47,7 @@ class MultipleFoldersVerify(object):
         self.message = message
 
     def __call__(self, form, field):
-        pattern = re.compile(r'^\w+(\s*,\s*\w+)*$')
+        pattern = re.compile(r'^[^,]+(,[^,]+)*$')
         if not pattern.match(field.data.replace(" ", "")):
             raise validators.ValidationError(self.message)