Yes, you should rewrite your query. If you explicitly code a UNION [ALL] into the query, Oracle takes it like a USE_CONCAT hint and does not attempt a transformation to enable the INLIST ITERATOR row source. Another problem with this query is that as written Oracle cannot replace the INTERSECT with a join. You also have several unwanted sorts. A better query would be

    select
      l.email
    from
      list l,
      rental r
    where
      l.list_id in (1, 2) and
        r.email = l.email and
      r.rental_id = 3 and
      r.client_id = 1
    minus
    select
      p.email
    from
      rental p
    where
      p.rental_id in (1, 2) and
      p.client_id = 1;

Does this mean that I can rewrite my query with the minuses and the unions to be a distinct where in? For example:

select email from
(
    (
    select email from list
    where list_id =1
    union
    select email from list
    where list_id =2
    )
    minus
    ( select email from rental
      where rental_id = 1
      and client_id = 1
      union
      select email from rental
      where rental_id = 2
        and client_id = 1
    )
)
intersect
( select email from rental
  where rental_id = 3
        and client_id = 1
);

select email from
(
    (
    select distinct email from list
    where list_id in (1,2)
    )
    minus
    ( select distinct email from rental
      where rental_id in ( 1,2 )
      and client_id = 1
      )
)
intersect
( select email from rental
  where rental_id = 3
        and client_id = 1
);