title: Mandrill "reject_reason": "invalid-sender"
body: <p>I'm trying to send emails using mandrill email service but I get the following error </p>
  
  <pre><code>    Full Response
  [
      {
          "email": "someemail@somedomain.com",
          "status": "rejected",
          "_id": "b814c2974594466cba9c904c54dca6c6",
          "reject_reason": "invalid-sender"
      }
  ]
  </code></pre>
  
  <p>Apart from the above error there is no more details about it. we are using .net to send emails with Mandrill SMTP settings.</p>