Everything is randomised, nothing is based real data. It's auto generated from popular first names, last names, changing patterns and random years or numbers attached at the end. Domains are real, but randomised as well.
It's kinda risky in my opinion. I just checked a few of the addresses (mostly the one's without any numbers at the end), some of them do actually belong to real people.
I was aiming for a feeling of dealing with real data (even though it's not). Changing the email domain names to fictitious ones will solve this, but I think would undermine the feeling of real-ness.