diff --git a/static/.well-known/mta-sts.txt b/static/.well-known/mta-sts.txt
index 58a522d..dad328f 100644
--- a/static/.well-known/mta-sts.txt
+++ b/static/.well-known/mta-sts.txt
@@ -1,5 +1,5 @@
 version: STSv1
-mode: testing
+mode: enforce
 mx: alt4.aspmx.l.google.com
 mx: alt3.aspmx.l.google.com
 mx: alt1.aspmx.l.google.com