RailsのActionMailerでメールを送信する（Gmail経由）

config.action_mailer.delivery_method = :smtp
config.action_mailer.raise_delivery_errors = true
config.action_mailer.smtp_settings = {
  :enable_starttls_auto => true,
  :address => 'smtp.gmail.com',
  :port => '587',
  :domain => 'smtp.gmail.com',
  :authentication => 'plain',
  :user_name => 'ユーザー名@gmail.com',
  :password => 'gmailパスワード'
}

# rails generate mailer クラス名　メソッド名

$ rails generate mailer NoticeMailer sendmail_confirm
      create  app/mailers/notice_mailer.rb
      invoke  erb
      create    app/views/notice_mailer
      create    app/views/notice_mailer/sendmail_confirm.text.erb
      invoke  test_unit
      create    test/functional/notice_mailer_test.rb

class NoticeMailer < ActionMailer::Base
  #デフォルトのヘッダ情報
  default from: "user@gmail.com"

  # Subject can be set in your I18n file at config/locales/en.yml
  # with the following lookup:
  #
  #   en.notice_mailer.sendmail_confirm.subject
  #
  def sendmail_confirm
    @greeting = "Hi"

    mail to: "user@sample.com", subject: "ActionMailer test"
  end
end

NoticeMailer#sendmail_confirm

<%= @greeting %>, find me in app/views/app/views/notice_mailer/sendmail_confirm.html.erb

<h2>テスト</h2>
<p>あいうえおかきくけこさしすせそたちつてとなにぬねのあいうえおかきくけこさしすせそたちつてとなにぬねのあいうえおかきくけこさしすせそたちつてとなにぬねのあいうえおかきくけこさしすせそたちつてとなにぬねのあいうえおかきくけこさしすせそたちつてとなにぬねのあいうえおかきくけこさしすせそたちつてとなにぬねの</p>

$ rails c
NoticeMailer.sendmail_confirm.deliver

  def mail_send
    @mail = NoticeMailer.sendmail_confirm.deliver
    render :text => 'send finish'
  end

<%= link_to 'Send Mail', action: "mail_send" %>