I have just received another phishing e-mail apparently from Paypal. Warning me about a transaction - that I did not authorise - and offering the the chance to challenge it by clicking a link in the e-mail. It looks authentic, however it is not. Under no circumstances should you click the link!
Paypal will never send one of these offers. Should you receive one, If you click on details of the sender, you will see that it is not Paypal. In my case it was a Hotmail account. You can log in to your account a see that the transaction has not happened.
Paypal customer service is available free on 0800 358 7911. They will confirm that the email is a scam and ask you to forward the email to firstname.lastname@example.org. They will then pursue action against the perpetrator.