#ifndef LIBRESSL_VERSION_NUMBER
# if OPENSSL_VERSION_NUMBER >= 0x010101000L
# define OPENSSL_HAVE_KEYLOG_CB
+# define OPENSSL_HAVE_NUM_TICKETS
# endif
#endif
else
DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
+#ifdef OPENSSL_HAVE_NUM_TICKETS
+SSL_CTX_set_num_tickets(ctx, 0); /* send no TLS1.3 stateful-tickets */
+#endif
+
/* We'd like to disable session cache unconditionally, but foolish Outlook
Express clients then give up the first TLS connection and make a second one
(which works). Only when there is an IMAP service on the same machine.