I haven't had one recently but at one time I was getting several every week. They quoted some fictitious customer reference number and told me that I had not paid and I was liable to be fined if I didn't follow the link and make a payment right away.
Fortunately, I earmark my annual receipts and I pay by DD so I was able to refer back to my latest receipt and the customer reference they quoted was nothing like the one on my genuine e-mail receipt. I reported it as a scam several times before I stopped receiving the messages.
I hope this is helpful.