Setup SendGrid SMTP

mailer.rb

class Mailer < ActionMailer::Base
  def test
    recipients "[email protected]"
    from "[email protected]"
    subject "Testing SendGrid"
  end
end

production.rb

config.action_mailer.raise_delivery_errors = true
config.action_mailer.delivery_method = :smtp
config.action_mailer.smtp_settings = {
  :address        => 'smtp.sendgrid.com',
  :port           => 25,
  :domain         => 'www.example.com',
  :authentication => :login,
  :user_name      => 'email',
  :password       => 'secret'
}

test.erb