Sailthru, an email analytics and personalization company that has worked with the likes of the Huffington Post, Fab and Thrillist, has just acquired Seamless Receipts, a digital receipts service. Since raising $8M in Series A funding last year, Sailthru has since grown rapidly, acquiring TechStars alum Frame and most recently a rumored ~$20M Series B round this month. Update: Sailthru has told TNW that they are in fact not raising right now.

The Frame acquisition padded Sailthru’s legitimacy on tablets, and now the company seems to be betting on digital receipts as a new way to reach existing customers — through marketing messages, coupons and other loyalty offers that have been packed into email receipts by retailers. It’s not hard to draw a connection as to why the buyout occurred, but it’s still an interesting direction for an email marketing company to go in.

From Sailthru:

It is with this accelerated spirit that I’m thrilled to announce the acquisition of Seamless Receipts. Seamless Receipts works with retailers to provide customers with electronic receipts. Beyond helping eliminate consumer paper-based clutter, their solution lets retailers provide customers with marketing messages, coupons and other loyalty offers. As the Seamless Receipts team comes to Sailthru, they bring experience working with many top retailers including Oakley, Burton and Tumi, who trust this technology to better serve their customers.

Seamless Receipts’ product and vision are well aligned with our mission to help our clients by delivering actionable, relevant and timely messages to their customers on a personalized, one-to-one basis. Over 35% of our customers exist in the eCommerce space, making Seamless Receipts a natural fit for our company as we continue to expand. Working together, we will continue to provide customers with personalized messaging, empowering more companies to ditch mass marketing for customized communications. The Seamless Receipts product will continue to operate as-is as part of the Sailthru family, and we are excited to welcome the team to work with us.

In addition to this announcement, Sailthru is also making changes to its pricing structure, and is now charging a fixed price per-user, versus per email sent. According to the release, this new model hopes to “incentivize relevant, well-targeted e-mails that keep customers engaged rather than bombarding them with undifferentiated messages.”

More than anything else, the success of this company goes to show exactly how much potential email still has — despite it being considered dead by many in this industry.