+/* If an authenticated_sender override has been specified for this transport
+instance, expand it. If the expansion is forced to fail, and there was already
+an authenticated_sender for this message, the original value will be used.
+Other expansion failures are serious. An empty result is ignored, but there is
+otherwise no check - this feature is expected to be used with LMTP and other
+cases where non-standard addresses (e.g. without domains) might be required. */
+
+if (ob->authenticated_sender != NULL)
+ {
+ uschar *new = expand_string(ob->authenticated_sender);
+ if (new == NULL)
+ {
+ if (!expand_string_forcedfail)
+ {
+ uschar *message = string_sprintf("failed to expand "
+ "authenticated_sender: %s", expand_string_message);
+ set_errno(addrlist, 0, message, DEFER, FALSE);
+ return ERROR;
+ }
+ }
+ else if (new[0] != 0) local_authenticated_sender = new;
+ }
+