diff --git a/lib/gitlab/email/receiver.rb b/lib/gitlab/email/receiver.rb
index df9d1cae8da6b9ed5b9d3908deea0cf6da5a0aea..fa08b5c668f07fc0a1b9403c519bb5e01368dab9 100644
--- a/lib/gitlab/email/receiver.rb
+++ b/lib/gitlab/email/receiver.rb
@@ -63,7 +63,9 @@ module Gitlab
         case references
         when Array
           references
-        when String # Handle emails from Microsoft exchange which uses commas
+        when String
+          # Handle emails from clients which append with commas,
+          # example clients are Microsoft exchange and iOS app
           Gitlab::IncomingEmail.scan_fallback_references(references)
         end
       end