Presell pages concept is based upon the credibility of the pages that provide you the backlinks; it’s all about content hosting, the most trustful the page where your link is, the better backlink you’ll get (this is called Google’s trust rank), with most qualified traffic heading to your domain. Presell pages are best for hosting content on some old and trusted authority sites (like .edus or .govs or rather old sites - minimum 2 year) related to your theme. From this authority bonus (also understood as trust) your own presell page will receive a bit of authority power and pass this on to your site to be marketed. In addition to getting some great links from that presell page, the presell page hosted on the authority site could give you a new SERP entry driving traffic to your site. That's because the hosting site is well established and has a great trust rank.
