I agree with others that this looks like a scam.
How did you check that 'it's a proper PayPal mail'? Did you check the originating server? If not, do this:
Open the mail fully (i.e. double-click on the subject line, so that the mail has its own window. Don't just read it in the preview pane).
Go to File > Properties. Then select the 'Details' tab.
Look at the 'Received' line. It should say something like 'from email-86.paypal.com'.
If the domain 'paypal.com' is in that line, then it's possible (or even probable) that the mail is genuine. If the domain name doesn't appear, then it's absolutely certain that it's a fake.
Chris