Whenever I see an email that appears like the subject is too vague for a corporation to send, I Google the words and add 'scam' to it. You would be surprised how many links come up with the scam alert recently dated. There is one out there since April for Expedited Shipping. I have gotten several lately too.
When ordering from Ebay, Etsy, etc. you can contact the seller immediately when you place the order. Ask them to place code words that you establish in the subject line whenever there is any correspondence from them. Most sellers I order from send a message if anything has progressed on the shipping. You can go to your message center in Ebay and check if they sent anything.