Another take on attachments deletion notification:

in case of Issues attachments make it obey to 'issue_update' setting rather than 'file_added'

app/controllers/attachments_controller.rb

@@ -49,9 +49,11 @@ def download
   end
 
   def to_notify?
-    notification_key = @attachment.container.notification_key if @attachment.container.respond_to?(:notification_key)
-    notification_key ||= NotificationKeys::FILE_ADDED
-    Setting.notified_events.include?(notification_key)
+    if @attachment.container.class.respond_to?(:notify?)
+      @attachment.container.class.notify?(:update)
+    else
+      Setting.notified_events.include?(NotificationKeys::FILE_ADDED)
+    end
   end
 
   def destroy

app/models/document.rb

@@ -35,7 +35,7 @@ def after_initialize
     end
   end
 
-  def notification_key
-    NotificationKeys::DOCUMENT_ADDED
+  def self.notify?(action)
+    Setting.notified_events.include?(NotificationKeys::DOCUMENT_ADDED)
   end
 end

app/models/issue.rb

@@ -283,6 +283,10 @@ def active_versions
     project.active_versions(:for => self)
   end
 
+  def self.notify?(action)
+    Setting.notified_events.include?(NotificationKeys.const_get('ISSUE_%sD' % action.to_s.upcase))
+  end
+
   private
 
   # Callback on attachment deletion

app/models/wiki_page.rb

@@ -126,8 +126,8 @@ def parent_title=(t)
     self.parent = parent_page
   end
 
-  def notification_key
-    NotificationKeys::WIKI_EDIT
+  def self.notify?(action)
+    Setting.notified_events.include?(NotificationKeys::WIKI_EDIT)
   end
 
   protected