@Prettypricklyplans: As pointed out, there are innumerable threads about this. Probably everyone in this forum can sympathize with you but as you will see by the innumerable threads about the exact same issue in this forum it is not likely to change.
The Star Seller metric is that the FIRST message of a NEW thread must be replied to within 24 hours. It does not matter who sent it, the subject matter, if it is a duplicate or blank or anything else. If it is SPAM then it should be marked as such. Those have always been the rules. Help Requests always start a new thread. By the way, if you are creating a custom listing based on a new thread, you still need to reply to the message. Etsy is now putting a blue text warning / advisory on those messages they consider to be a "new message" but should semantically be called a "new thread".
Help Requests always start a new thread and if you are creating a custom listing based on a new thread, you still need to reply to the message. .
At least for the time being, it appears that marking an unanswered message as SPAM (even after the 24 hour deadline has passed) will cause your reply percentage to change in a day or two if the original message was within the current star seller period.
If you have not yet done so, you might want to read https://help.etsy.com/hc/en-us/articles/4403058372503-How-to-Become-a-Star-Seller?segment=selling
