Hi,
Alessio is correct: Sent rules are not managed at the moment.
Only the interface is there, so it's possible to load rules for both in and out, but then "in rules" are translated into sieve rules and installed, but we have not developed any logic for "out rules" yet.
Hope this is not such an important feature, because we still have no plan for it on this major release, while we have plans for the next major.
Gabriele