title: Ruby on rails mailer + Mailgun marked as spam
body: <p>I have a ActionMailer with following settings(according to <a href="http://blog.mailgun.com/post/tips-tricks-avoiding-gmail-spam-filtering-when-using-ruby-on-rails-action-mailer/" rel="nofollow">this</a> guide):</p>
  
  <pre><code>require 'digest/sha2'
  class WinnerMailer &lt; ActionMailer::Base
    include Resque::Mailer
    default "Message-ID"=&gt;"&lt;#{Digest::SHA2.hexdigest(Time.now.to_i.to_s)}@my-domain.com&gt;"
    default from: "mail@my-domain.com"
  </code></pre>
  
  <p>My email has:</p>
  
  <pre><code>From: mail@my-domain.com
  To: xxx@gmail.com
  Message-Id: &lt;50117ee0355959752a01b1737c8568f30ea72db2f35ec68cfa7808cea18dbb69@my-domain.com&gt;
  </code></pre>
  
  <p>My <code>production.rb</code> has following settings:</p>
  
  <pre><code>  config.action_mailer.delivery_method = :smtp
    config.action_mailer.perform_deliveries = :true #try to force sending in development
    config.action_mailer.raise_delivery_errors = :false
    config.action_mailer.smtp_settings = {
        :authentication =&gt; :plain,
        :address =&gt; "smtp.mailgun.org",
        :port =&gt; 587,
        :domain =&gt; "my-domain.com",
        :user_name =&gt; "postmaster@my-domain.com",
        :password =&gt; "qqqqq"
    }
  </code></pre>
  
  <p>For some reasons all my letters go to spam folder. What am I doing wrong?</p>