diff -ruN netqmail-1.06-old/qmail-smtpd.c netqmail-1.06/qmail-smtpd.c
--- netqmail-1.06-old/qmail-smtpd.c	2022-01-17 18:20:36.287701251 +0100
+++ netqmail-1.06/qmail-smtpd.c	2022-02-13 15:53:45.386236334 +0100
@@ -2347,13 +2347,18 @@
   /* renegotiation should include certificate request */
   SSL_CTX_set_options(ctx, SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION);
 
+  /* Disables all renegotiation in TLSv1.2 and earlier (TLS Renegotiation vulnerability) */
+#ifdef SSL_OP_NO_RENEGOTIATION
+  SSL_CTX_set_options(ctx, SSL_OP_NO_RENEGOTIATION);
+#endif
+
   /* never bother the application with retries if the transport is blocking */
   SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
 
   /* relevant in renegotiation */
   SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);