development.rb

# config/environments/development.rb

# add this line
config.action_mailer.delivery_method = :test

my_mailer.rb

# app/models/my_mailer.rb

class MyMailer < ActionMailer::Base
	def test_message(content)
		recipients '[email protected]'
		from '[email protected]'
		subject 'Test Message'
		body content
	end
end

test_controller.rb

# app/controllers/test_controller.rb

class TestController < ApplicationController
	def send_mail
		MyMailer.deliver_test_message('Hi There.')
		render :nothing => true
	end
end