diff --git a/lib/noosfero/plugin.rb b/lib/noosfero/plugin.rb
index 6db0ae9..4feba9f 100644
--- a/lib/noosfero/plugin.rb
+++ b/lib/noosfero/plugin.rb
@@ -226,12 +226,55 @@ class Noosfero::Plugin
   # example:
   #
   #   def filter_comment(comment)
-  #     comment.reject! if anti_spam_service.is_spam?(comment)
+  #     if user_not_logged_in
+  #       comment.reject!
+  #     end
   #   end
   #
   def filter_comment(comment)
   end
 
+  # This method is called by the CommentHandler background job before sending
+  # the notification email. If the comment is marked as spam (i.e. by calling
+  # <tt>comment.spam!</tt>), then the notification email will *not* be sent.
+  #
+  # example:
+  #
+  #   def check_comment_for_spam(comment)
+  #     if anti_spam_service.is_spam?(comment)
+  #       comment.spam!
+  #     end
+  #   end
+  #
+  def check_comment_for_spam(comment)
+  end
+
+  # This method is called when the user manually marks a comment as SPAM. A
+  # plugin implementing this method should train its spam detection mechanism
+  # by submitting this comment as a confirmed spam.
+  #
+  # example:
+  #
+  #   def comment_marked_as_spam(comment)
+  #     anti_spam_service.train_with_spam(comment)
+  #   end
+  #
+  def comment_marked_as_spam(comment)
+  end
+
+  # This method is called when the user manually marks a comment a NOT SPAM. A
+  # plugin implementing this method should train its spam detection mechanism
+  # by submitting this coimment as a confirmed ham.
+  #
+  # example:
+  #
+  #   def comment_marked_as_ham(comment)
+  #     anti_spam_service.train_with_ham(comment)
+  #   end
+  #
+  def comment_marked_as_ham(comment)
+  end
+
   # -> Adds fields to the signup form
   # returns = lambda block that creates html code
   def signup_extra_contents
--
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