From 1a81a89d4ee46867ea405ac09fc55309a0337c82 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Tue, 26 Dec 2023 10:08:29 +0100
Subject: [PATCH 1/1] prevent SMTP smuggling

---
 roles/email/templates/main.cf | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/roles/email/templates/main.cf b/roles/email/templates/main.cf
index 45c77d3..2d254f0 100644
--- a/roles/email/templates/main.cf
+++ b/roles/email/templates/main.cf
@@ -65,6 +65,11 @@ smtpd_recipient_restrictions = permit_mynetworks, permit_tls_clientcerts,
     reject_non_fqdn_recipient,
     reject_non_fqdn_sender,
 
+# SMTP smuggling protection
+# <https://www.postfix.org/smtp-smuggling.html>
+smtpd_data_restrictions = reject_unauth_pipelining
+smtpd_discard_ehlo_keywords = chunking
+
 {% if postfix.relay_host is defined %}
 # Relay everything
 default_transport = smtp:{{ postfix.relay_host }}
-- 
2.30.2