diff --git a/docs/topics/email.txt b/docs/topics/email.txt
index 6b93d7d2b8..84c108876d 100644
--- a/docs/topics/email.txt
+++ b/docs/topics/email.txt
@@ -457,6 +457,9 @@ SMTP backend
         Then point the :setting:`EMAIL_BACKEND` setting at your custom backend as
         described above.
 
+        If unspecified, the default ``timeout`` will be the one provided by
+        :func:`socket.getdefaulttimeout()`, which defaults to ``None`` (no timeout).
+
 .. _topic-email-console-backend:
 
 Console backend