User Activity

Is there an easy way to identify if I have a return buyer with orders? I saw something on one seller hub page but haven't been able to find it again.Thanks in advance.
I have been selling for less than a month, a few weeks ago I saw one, then two "unanswered messages" in my Active list, all the listings give the same result - "...invalid or older than 90 days..." This is nonsense! Do I have messages from buyers I h...