When my credit card on file with PayPal was expiring, they did send me an email about it.
Being wise I did not use any "link" in the message, but logged into my PayPal account directly and indeed the credit card was out of date.
Any email correspondence is SAFE to believe IF you NEVER connect via the provided link... Rather go the your usual log in via the original web address, and see if the request is in your account info.
Is, it's valid, if not, report the fraudulent email.