Short Answer: No. Private Blog Networks (PBNs) do not work for SEO. This was a Web 2.0 tactic used by search engine optimization (SEO) professionals to boost the ranking of websites. This tactic is outdated and while it may have worked in 2010, it doesn't work in today's time. So therefore, if you get an unsolicited email from an unscrupulous SEO scammer telling you that he will add your website to a network of blogs and other websites, then you are in for a world of hurt. Just note that these scammers may not use the term PBN or Private Blog Network, they will just tell you that they will backlink you to a bunch of websites.