if a question was answered, all occurrences of it in the inbox are now gone

app/models/answer.rb

@@ -5,6 +5,8 @@ class Answer < ActiveRecord::Base
   has_many :smiles, dependent: :destroy
 
   after_create do
+    Inbox.where(user: self.user, question: self.question).destroy_all
+
     Notification.notify self.question.user, self unless self.question.author_is_anonymous
     self.user.increment! :answered_count
     self.question.increment! :answer_count