title: Rails, passing an object to mailer
body: <p>I've got a theoretical question about mailer in Rails.
  I've heard a pair of times that passing resources directly to mailer is not considerated as good practice. And that is its better simply pass an id to load the object. For example exactly this thing is said in the accepted answer in this question: <a href="https://stackoverflow.com/questions/4337879/rails-absolutely-stumped-with-delayed-job-not-receiving-arguments-anywhere">Rails: Absolutely stumped with delayed_job. Not receiving arguments anywhere</a></p>
  
  <p>But if it is so, what are the reasons of this prohibition? I can not treat linked question as an exhaustive explanation.
  Thank you for your suggestions.</p>