diff --git a/bundles/postfix/files/main.cf b/bundles/postfix/files/main.cf
index d3ad792..3c0e190 100644
--- a/bundles/postfix/files/main.cf
+++ b/bundles/postfix/files/main.cf
@@ -37,6 +37,8 @@ smtpd_tls_auth_only = yes
 smtpd_tls_cert_file = /var/lib/dehydrated/certs/${hostname}/fullchain.pem
 smtpd_tls_key_file = /var/lib/dehydrated/certs/${hostname}/privkey.pem
 smtp_tls_security_level = may
+smtpd_tls_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
+smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
 
 smtpd_restriction_classes = mua_sender_restrictions, mua_client_restrictions, mua_helo_restrictions
 mua_client_restrictions = permit_sasl_authenticated, reject