Definition no_msg_from_to from to (d : soup) :=
forall i tms b,
find i d = Some (Msg tms from to b) -> b = false.

Lemma msg_specE_consume s pt from to to' tg cnt i m :
valid s ->
find i s =
Some {| content := m; from := from; to := to'; active := true |} ->
(pt != from) || (to != to') ->
msg_spec pt to tg cnt s ->
msg_spec pt to tg cnt (consume_msg s i).