Log when and why an email was not sent in email_logs

db/migrate/20140214151255_add_skipped_to_email_logs.rb

@@ -0,0 +1,7 @@
+class AddSkippedToEmailLogs < ActiveRecord::Migration
+  def change
+    add_column :email_logs, :skipped, :boolean, default: :false
+    add_column :email_logs, :skipped_reason, :string
+    add_index  :email_logs, [:skipped, :created_at]
+  end
+end