#app/controllers/feedback_info_controller.rb

def send_mail
 smtp = Net::SMTP.new( "smtp.yandex.ru", 587 )
 smtp.enable_starttls
 smtp.start( "yandex.ru", "my_adr@yandex.ru", "пароль", :plain ) do |conn|
 conn.send_message "Сообщение", "my_adr@yandex.ru", "получатель@rambler.ru"
end

by mx2.mail.rambler.ru (Postfix) with ESMTP id 65FF15CA8
    for <получатель@rambler.ru>; Mon, 24 Aug 2015 11:13:46 +0300 (MSK)

by forward22m.cmail.yandex.net (Yandex) with ESMTP id 488F18046B
    for <получатель911@rambler.ru>; Mon, 24 Aug 2015 11:13:46 +0300 (MSK)

by smtp3m.mail.yandex.net (Yandex) with ESMTP id 2C1A127A05B8
    for <получатель911@rambler.ru>; Mon, 24 Aug 2015 11:13:46 +0300 (MSK)

#app/mailers/application_mailer.rb
    class ApplicationMailer < ActionMailer::Base
    end

   #app/mailers/feedback_mailer.rb
    class FeedbackMailer < ApplicationMailer
    def feedback_email
      mail(from: 'my_adr@yandex.ru', to: 'получатель@rambler.ru', subject: 'тема')
    end
    end

   #app/controllers/feedback_info_controller.rb
    def feedback_send
       FeedbackMailer.feedback_email
    end

  #config/environments/development.rb
    config.action_mailer.default_url_options = { host: 'localhost', port: 3000 }
    config.action_mailer.delivery_method = :smtp
    config.action_mailer.smtp_settings = {
        address: 'smtp.yandex.ru',
        port: 587,
        domain: 'yandex.ru',
        authentication: 'plain',
        user_name: 'my_adr@yandex.ru',
        password: 'пароль',
        enable_starttls_auto: true
    }