title: Error in SendGrid on Heroku cedar stack
body: <p>when I try to send an email via sendgrid on heroku cedar stack,
  I got an following error : </p>
  
  <pre><code>ArgumentError (SMTP-AUTH requested but missing user name):
  </code></pre>
  
  <p>my settings in /environments/staging.rb are : </p>
  
  <pre><code>  config.action_mailer.delivery_method = :smtp
    config.action_mailer.raise_delivery_errors = true
    config.action_mailer.default_url_options = { :host =&gt; 'myapp' }
  
    ActionMailer::Base.smtp_settings = {
      :address        =&gt; "smtp.sendgrid.net",
      :port           =&gt; "587",
      :authentication =&gt; :plain,
      :user_name      =&gt; ENV['SENDGRID_USERNAME'],
      :password       =&gt; ENV['SENDGRID_PASSWORD'],
      :domain         =&gt; 'heroku.com'
    }
  </code></pre>
  
  <p>My Sendgrid password/username are obtained from Heroku according to <a href="https://devcenter.heroku.com/articles/sendgrid" rel="nofollow">this page</a></p>
  
  <p>Does anyone have any suggestion ?</p>