
It's a notification email saying that payment has been received from buyer. For an ordinary merchant, it's well, payment received and all set to ship the items.
In this case, this merchant has shipped the items without much hesitation, as clothings apparently carry a lower fraud risk.
However, the merchant has received another email from PayPal a few hours later. This time, it's about a case being raised on the said transaction and the related funds have been placed on a temporary hold.
At first thought, this sounds like a fraudulent transaction as the buyer has possibly cancelled the payment. So, this merchant has called the buyer to clarify but the buyer has denied reversing the payment.