It looked legit but you know how wary you have to be, so I did a search and wasn't really able to find anything.
My stats show in the last week there has been 5 referrals under 'traffic sources' from this site, and 6 in the month. It appears to have ramped up in the last 7 days.
The email comes from purebloggerss@gmail.com (with a double 's') and it looks like this:

Kek 60p · 683 weeks ago
Nobody has heard of them, and yet they claim to be the biggest blog network...? Compare their log-in page to Facebook's and you can see that they've directly ripped off FB's template and even some of the text. That concerns me....
Check out some of the posts about them when you Google "who is pure blogger.com" You're right to be wary.
Kek 60p · 683 weeks ago
You can view this page quite safely (at least I did): http://purebloggers.com/blog/ Many of the same "blogs" appear in all categories, and two that I clicked on are nothing more than "scraper" sites. The posts are most likely stolen from other sites and posted as original material, to capture search engine traffic. Why? Because they have ads EVERYWHERE.
Unfortunately, it looks as though some unsuspecting genuine bloggers have signed up, which is going to lend the site legitimacy (and give it more traffic).
designedtoat 11p · 683 weeks ago
Kylie · 683 weeks ago
tessa · 676 weeks ago