+#ifdef EXPERIMENTAL_DSN
+extern uschar *dsn_envid; /* DSN envid string */
+extern int dsn_ret; /* DSN ret type*/
+extern const pcre *regex_DSN; /* For recognizing DSN settings */
+extern BOOL smtp_use_dsn; /* Global for passed connections */
+extern uschar *dsn_advertise_hosts; /* host for which TLS is advertised */
+#endif