If you do notice that the 'Reference' field isn't populated for your messages on Seller Central, you don't have to worry about it, this field is optional and we will still be sending emails to your buyers.

If you do wish to get the 'Reference' field automatically filled with the Order ID, all you would need to do is simply add (Order: [#order-id#]) in the Subject of your message in feedBAKER and this would then populate it on Seller Central.