config/environments/development.rb に以下を書くだけ。 config.action_mailer.default_url_options = { :host => "localhost", :port => 3000 } config.action_mailer.delivery_method = :smtp config.action_mailer.smtp_settings = { :address => "smtp.gmail.com", :port => 587, :domain => 'example.com', :user_name => "FOO@example.com", :password => "PASSWORD", :authentication => 'plain', :enable_starttls_auto => true, }