diff --git a/reviewboard/notifications/email.py b/reviewboard/notifications/email.py
--- a/reviewboard/notifications/email.py
+++ b/reviewboard/notifications/email.py
@@ -193,6 +193,8 @@ def send_review_mail(user, review_request, subject, in_reply_to,
     headers = {
         'X-ReviewBoard-URL': base_url,
         'X-ReviewRequest-URL': base_url + review_request.get_absolute_url(),
+        'X-ReviewGroup': ', '.join(group.name for group in \
+                                    review_request.target_groups.all())
     }
 
     sender = None