Which emails from Norton are legitimate and which are fraudulent?

I've been getting offers from what truly looks as if it is from Norton/Lifelock for the past year. Each message proposes renewing with a 50% discount. It is very difficult to get through to a live representative from Norton, but when I did a few months ago, he reaffirmed that Norton did not have a 50% discount renew deal. I just received another email this week with the following text:

This came from: Norton <offer@nortonsubscription.com>

Title of email: How to benefit from a year's extra security

Text of email:

Norton 360. Comprehensive protection with device security including antivirus, plus a VPN, a password manager and more. All in a single solution. Norton technology blocks over 7 million threats per day, on average and we have over 25 years of consumer cyber security experience. Get your existing Norton subscription renewed and avail 50% discount.

Coupon Code: SALP405 (this coupon code has been consistent with all previously received offers)

A link to 'get more details' leads to this page:

There are no agents available right now to take your call. Please leave a message and we will reply by email.

-end of email-

I do not respond to any emails from Norton anymore because I have no way of determining whether messages are legitimate.

Check it versus this Norton page.

https://support.norton.com/sp/en/us/home/current/solutions/v71088498