Paypal just lets peole send invoice spam. It's a known problem and apparently won't fix it.
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.