D@nmed Norton again...sending me another notice that "my Norton 360 has expired" when I have about 410 days remaining! Lousy company. Lousy advertising. Symantic fails again!
First check that the email is a legitimate Norton email. Check the sender's address against this Norton Support article. Is this email from Norton legitimate? If it is not on that list it is a scammer. Do not click on any links in the email or phone any phone numbers.
If it is a genuine Norton email, have you recently renewed your Norton subscription using a new product key you purchased? If so, these emails could be for your old subscription which would have expired. Those emails should stop after about 30 days.