Shortcode for notes?

Hi

I want to include the order notes/comments (if any) to the e-mail subject so I can quickly see in my inbox if an order has comments. I tried adding {order_notes} or {order_note} to the e-mail subject for the New order e-mail sent to me, but neither of those codes does it. Is there any way to add them to the subject?

Thank you.

Best regards, Rasmus.