Lately when I visit a website, I'm getting promo emails from them even when I HAVEN'T provided my email. Is this legal?

I noticed that after I visit a website, I get an email from them. They're promo emails (e.g. "Thanks for stopping by! Here's 10% off")

I haven't given them my email. I simply just visited!

What's also curious is I used another device and the same thing happens. I assume its because I'm logged into gmail and somehow they're seeing my gmail account

How is this happening? Is this legal? Anything I can do or report to? Located in California

email emails legal privacy promo website