diff --git a/app/notify_client/notification_api_client.py b/app/notify_client/notification_api_client.py
index 341d10234..793af02ef 100644
--- a/app/notify_client/notification_api_client.py
+++ b/app/notify_client/notification_api_client.py
@@ -63,6 +63,7 @@ class NotificationApiClient(NotifyAdminAPIClient):
         data = {
             'filename': filename,
             'file_id': file_id,
+            'postage': 'second',
         }
         data = _attach_current_user(data)
         return self.post(url='/service/{}/send-pdf-letter'.format(service_id), data=data)
diff --git a/tests/app/notify_client/test_notification_client.py b/tests/app/notify_client/test_notification_client.py
index 1975a3412..eee76a981 100644
--- a/tests/app/notify_client/test_notification_client.py
+++ b/tests/app/notify_client/test_notification_client.py
@@ -71,7 +71,8 @@ def test_send_precompiled_letter(mocker, logged_in_client, active_user_with_perm
         data={
             'filename': 'my_file.pdf',
             'file_id': 'file-ID',
-            'created_by': active_user_with_permissions['id']
+            'created_by': active_user_with_permissions['id'],
+            'postage': 'second',
         }
     )