send email when exception has occurred not working , using exception_notification

I am migrating from rails 2.3 to rails 3.1, I am trying to send a email when exception is generated. I am using exception_notification gem.

My rest of the emails are working. But exception mail is not getting fired.

below are the settings in my staging.rb file.

config.action_mailer.perform_deliveries = true
config.action_mailer.raise_delivery_errors = true

and following is the code in application.rb

C::Application.config.middleware.use ExceptionNotification::Rack, :email => { :email_prefix => "[#{Rails.env.to_s.upcase} Error] ", :sender_address => %{"Exception Notifier " }, :exception_recipients => %w{email_id} }

I am not sure why the email is not triggering, nor do i see any error. Any help would be appriciated, Thanks.