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