+Returns: nothing
+*/
+
+static void
+print_dsn_diagnostic_code(const address_item *addr, FILE *f)
+{
+uschar * s;
+
+/* check host_used, af_pass_message flag and addr->message for safety reasons */
+if (!addr->host_used && testflag(addr, af_pass_message) && addr->message)
+ return;
+
+/* search first ": ". we assume to find the remote-MTA answer there */
+DEBUG(D_deliver)
+ debug_printf("DSN Diagnostic-Code: addr->dsn_message = %s\n", addr->message);
+if (!(s = Ustrstr(addr->message, ": ")))
+ return; /* not found, bail out */
+
+fprintf(f, "Diagnostic-Code: smtp; ");
+
+s += 2; /* skip ": " */
+while (*s)
+ if (*s == '\\' && s[1] == 'n')
+ {
+ fputs("\n ", f); /* as defined in RFC 3461 */
+ s += 2;
+ }
+ else
+ fputc(*s++, f);
+
+fputc('\n', f);
+}