Two reasons why its not a proper invoice. 1) I checked the mobile app, web page and any mention of this on my account and it never made it there.

2) The format of the email leads me to question it, the top part has the text: " Hello, Suspicious transaction of $399.90 detected. If not done by you contact Fraud Investigation team at +1 (833) 902-0431 to cancel. Service hours(9AM-6PM) Email cs-billings@hilton.com"

Is there a free HTML text field for sending invoice? And how did the break out of the email box and get to the top. This would be easier with a picture.