title: Add custom metadata when sending an email using mandrill and receive metadata in an inbound event
body: <p>i will like to know if there is a way to <strong>add custom metadata when sending an email using the mandrill API (/messages/send.json) and receive this metadata in an inbound event</strong>. I know that there is a way as it's explained here <a href="https://mandrill.zendesk.com/hc/en-us/articles/205582417-Using-Custom-Message-Metadata" rel="nofollow">https://mandrill.zendesk.com/hc/en-us/articles/205582417-Using-Custom-Message-Metadata</a>; but i am afraid this metadata will not be included in <a href="https://mandrill.zendesk.com/hc/en-us/articles/205583207-What-is-the-format-of-inbound-email-webhooks-" rel="nofollow">inbound emails</a>, only in <a href="https://mandrill.zendesk.com/hc/en-us/articles/205583307-Message-Event-Webhook-format" rel="nofollow">message events</a></p>
  
  <p>Is it possible to receive custom metadata (or custom fields) in inbound emails?</p>
  
  <p>Thanks</p>