diff --git a/homeassistant/components/notify/smtp.py b/homeassistant/components/notify/smtp.py
index fc38647a065..e3a6f8b85b1 100644
--- a/homeassistant/components/notify/smtp.py
+++ b/homeassistant/components/notify/smtp.py
@@ -151,10 +151,10 @@ class MailNotificationService(BaseNotificationService):
         if data:
             if ATTR_HTML in data:
                 msg = _build_html_msg(
-                    message, data[ATTR_HTML], images=data.get(ATTR_IMAGES))
+                    message, data[ATTR_HTML], images=data.get(ATTR_IMAGES, []))
             else:
                 msg = _build_multipart_msg(
-                    message, images=data.get(ATTR_IMAGES))
+                    message, images=data.get(ATTR_IMAGES, []))
         else:
             msg = _build_text_msg(message)