when ever you receive a message from paypal requesting anything you should not respond to the email- you should contact them directly- then you know you are dealing with them & not some hacker-
as QKO mentioned above the government has (forced) some new rules- not paypal's choice- but when the government decides things have to change it's hard to fight it.
but don't give your ss# to an email message- contact paypal and find out if they need information from you- and realize- it is not that they want to deal with more paper work- the irs wants to make sure they get their share...