1 files changed, 13 insertions, 0 deletions
diff --git a/lib/gitlab/email/receiver.rb b/lib/gitlab/email/receiver.rb
index 0d6b08b5d29..c8f4591d060 100644
--- a/lib/gitlab/email/receiver.rb
+++ b/lib/gitlab/email/receiver.rb
@@ -26,6 +26,9 @@ module Gitlab
         raise EmptyEmailError if @raw.blank?
 
         mail = build_mail
+
+        ignore_auto_submitted!(mail)
+
         mail_key = extract_mail_key(mail)
         handler = Handler.for(mail, mail_key)
 
@@ -87,6 +90,16 @@ module Gitlab
           break key if key
         end
       end
+
+      def ignore_auto_submitted!(mail)
+        # Mail::Header#[] is case-insensitive
+        auto_submitted = mail.header['Auto-Submitted']&.value
+
+        # Mail::Field#value would strip leading and trailing whitespace
+        raise AutoGeneratedEmailError if
+          # See also https://tools.ietf.org/html/rfc3834
+          auto_submitted && auto_submitted != 'no'
+      end
     end
   end
 end