diff --git a/README.md b/README.md
index c4354b28..8c7d1640 100644
--- a/README.md
+++ b/README.md
@@ -22,7 +22,7 @@ Main features include:
 - **Web access**, multiple Webmails and administration interface
 - **User features**, aliases, auto-reply, auto-forward, fetched accounts
 - **Admin features**, global admins, announcements, per-domain delegation, quotas
-- **Security**, enforced TLS, Letsencrypt!, outgoing DKIM, anti-virus scanner
+- **Security**, enforced TLS, MTA-STS, Letsencrypt!, outgoing DKIM, anti-virus scanner
 - **Antispam**, auto-learn, greylisting, DMARC and SPF
 - **Freedom**, all FOSS components, no tracker included