(define (make-mailbox phrase route-addr)
  (let ((e (new-email-address)))
    (assert-phrase     phrase)
    (assert-route-addr route-addr)

    (set e 'name phrase)

    (let ((route     (first route-addr))
          (addr-spec (second route-addr)))
      (assert-route     route)
      (assert-addr-spec addr-spec)

      (set e 'route route)
      (set-addr-spec e addr-spec))

    e))

(define mailbox-2
  (sequence* ((phrase phrase)
              (_ (zero-or-more linear-white-space))
              (route-addr route-addr))
    (result (make-mailbox phrase route-addr))))