Mark McCreary wrote,
| If I change the order of the arguments, it does not dump core, although it
| does not return an answer either. That is
|
| formail -rtxzTo: <test-file
That's for a different reason. The -x and -X options need to be followed
by the name of a header field, so that is equivalent to this:
formail -rtx Zto: <test-file
Since the reply header generated by formail -rt won't have any field named
Zto: (even if the message in test-file does have a header named Zto:), there
will be no output.