email-tIt’s become a cliche that mobile should come first these days, but there’s another split in online audiences that is just as important. I’m talking about the division between logged-in and not-logged-in visitors.

Logged-in users are valuable, because their email address can be used to track them across multiple devices – an effective replacement for cookies in a world where cookies are increasingly blocked.  That trackability and identification allows email messages to be updated and customized in realtime, as the recipient opens the message.

From an affiliate marketing perspective, what this means is that a new opportunity for cost-effective traffic is opening up. Imagine buying cheap email ads that can be optimized according to the recipient’s Facebook profile or purchase history with Safeway.

Email hashing – the process by which an email address is converted into a hexadecimal string – enables Facebook’s Custom Audiences premium offering,  Twitter’s Tailored Audiences, Movable Ink’s realtime email customization (in which the content of the email is updated when it is opened) and, more recently, LiveIntent’s LiveAudience ad exchange for programmatic email ad bidding.

It brings email into a similar big data environment as other programmatic bidding media, with all the same complexities but also the same kind of opportunities. Moveable Ink CEO Vivek Sharma, says:

“Email is the highest ROI digital marketing channel available to a brand. On average, it’s about $30 return on investment for every dollar spent.”

Affiliate marketers make much of their money from pushing the envelope and exploring new opportunities. Maybe good old email is the next new frontier?

More on programmatic email here.