diff --git a/tools/c7n_mailer/c7n_mailer/email_delivery.py b/tools/c7n_mailer/c7n_mailer/email_delivery.py
index e25ff7d1a97..a9382b6f3d4 100644
--- a/tools/c7n_mailer/c7n_mailer/email_delivery.py
+++ b/tools/c7n_mailer/c7n_mailer/email_delivery.py
@@ -43,10 +43,10 @@ def get_valid_emails_from_list(self, targets):
                 # gcp doesn't support the '@' character in their label values so we
                 # allow users to specify an email_base_url to append to the end of their
                 # owner contact tags
-                if not is_email(target) and self.config.get('email_base_url'):
-                    target = "%s@%s" % (target, self.config['email_base_url'])
-                    if is_email(target):
-                        emails.append(target)
+                if not is_email(email) and self.config.get('email_base_url'):
+                    full_email = "%s@%s" % (email, self.config['email_base_url'])
+                    if is_email(full_email):
+                        emails.append(full_email)
         return emails
 
     def get_event_owner_email(self, targets, event):  # TODO: GCP-friendly
diff --git a/tools/c7n_mailer/tests/test_email.py b/tools/c7n_mailer/tests/test_email.py
index d4d07b3fc34..51529844166 100644
--- a/tools/c7n_mailer/tests/test_email.py
+++ b/tools/c7n_mailer/tests/test_email.py
@@ -363,3 +363,12 @@ def test_get_ldap_connection(self):
             )
             patched.assert_called()
             self.assertEqual(delivery.config['ldap_bind_password'], "a password")
+
+    def test_get_valid_emails_from_list_gcp(self):
+        delivery = EmailDelivery(
+            {'ldap_uri': 'foo', 'email_base_url': 'example.com'},
+            self.aws_session, MagicMock())
+        result = delivery.get_valid_emails_from_list(['resource-owner', 'foo:bar'])
+        self.assertEqual(len(result), 2)
+        self.assertTrue('foo@example.com' in result)
+        self.assertTrue('bar@example.com' in result)