Need an idea for a complex SQL question
It sounds like what you're looking for is the list of communications for which there is no accepted message. You're only interested in checking for communications where there is at least one rejection, so the logic might be something like:

select distinct communications
where  the status is rejection
and there does not exist an acceptance for that communication.


Alternatively, you could check the status on the record with the highest received timestamp for each communication to ensure that it is an acceptance.