Guild Wars 2

so i am trying to get the achievement in which you must do all the hints the game gives you and im stuck on the one that says i have to delete a letter in my inbox folder in order to finish the achievement. Ive done everything its says (delete a letter) and yet i still dont have it completed. Help me please, im trying to get achievement points for the rewards which are awesome by the way.

You have to have 10 emails in your inbox, from other players, not NPCs.