+#ifdef EXPERIMENTAL_DSN
+/* Flags for recipient_block, used in DSN support */
+
+#define rf_dsnlasthop 0x01 /* Do not propagate DSN any further */
+#define rf_notify_never 0x02 /* NOTIFY= settings */
+#define rf_notify_success 0x04
+#define rf_notify_failure 0x08
+#define rf_notify_delay 0x10
+
+#define rf_dsnflags (rf_notify_never | rf_notify_success | \
+ rf_notify_failure | rf_notify_delay)
+
+/* DSN RET types */
+
+#define dsn_ret_full 1
+#define dsn_ret_hdrs 2
+
+#define dsn_support_unknown 0
+#define dsn_support_yes 1
+#define dsn_support_no 2
+
+#endif
+