Used stamps exchanges.

Yesterday I received a ltter and gave a 4 at first sight. After sorting the stamps a second time I had to change to a 3, unfortunately.
With rating 3, this member should be in the blocked member list. This didn't not work out.
When you upgrade a rating e.g. from 3 to 4, this member remains in the blocking list.

Recently I added an option "Block this member from future exchanges." when you register an exchange. In this way, you can still block a member even if you give 5 stars if for some reason you want to do so.

You have a link "Blocked members" in the left menu. On that page you can view who's on the list and also you have there options to remove members from the list.