Can websites scan anonymous web traffic and personally identify visitors ?

This guy visited without providing any personal info or being logged into any service and a day later, he got an email from them:

Recently, I visited the landing & pricing page at I did not signup for anything, did not leave my email, did not connect with any of their social media properties.  One day later, I get an email (see attached image).

I’m sure they triangulated some information but how could they pin point to personally identify me? Is this common & so blatant (or even legal)?

Interesting discussion over at Hacker News that triangulates it down to two tracking services– Trackalyzer and LeadlanderCan websites personally identify visitors? | Hacker News.