diff --git a/kallithea/lib/helpers.py b/kallithea/lib/helpers.py
--- a/kallithea/lib/helpers.py
+++ b/kallithea/lib/helpers.py
@@ -479,7 +479,7 @@ def is_hg(repository):
 
 def user_or_none(author):
     email = author_email(author)
-    if email is not None:
+    if email:
         user = User.get_by_email(email, case_insensitive=True, cache=True)
         if user is not None:
             return user