A quick hack to make Devise send its confirmation/password reset/unlock emails via delayed_job. Chuck the following in a file under config/initializers

delayed_devise_mailer.rb

module Devise
  module Models
    module Confirmable
      handle_asynchronously :send_confirmation_instructions
    end
	
    module Recoverable
      handle_asynchronously :send_reset_password_instructions
    end
		
    module Lockable
      handle_asynchronously :send_unlock_instructions
    end
  end
end