I had a buyer send me 3 separate messages within a ten minute period because they forgot to include needed information. Because I did not respond to each individual message I didn't get Star Seller status! It would have been ridiculous to respond to each message individually! I responded within minutes but only to the last one. I'm not a fan of this system.
You must reply to all or mark as spam.
Mark the other messages as spam. That works. Easy Peasy.