At some point in the future, almost all direct mail will be personalized to reflect all the data the sender has accumulated or discovered about us, including our past actions–online and off. That's because, as recipients, we are more likely to respond to highly personalized mail, making the mailing effort more profitable.  

In the meantime, the first company to provide physical direct mailings that integrate online consumer tracking data is PebblePost. Founder Lewis Gersh says… 

PebblePost is proud to announce the invention of Programmatic Direct Mail, which applies digital thinking to direct mail to help marketers drive great results. For example:

Website activity feeds direct mail segments. Through a simple tag, PebblePost identifies the best segment and offer for the visitor. This digital data kicks off the printing and sending of a mail piece, which arrives at the consumer’s door in three days.
Attribution of mail closes the digital loop. With a known recipient of the mail, marketers can track the funnel of return visits, overall conversions, and redemption of promotions when an offer is included.

PebblePost Blog: How to Close the Deal with Programmatic Direct Mail®, 2018-Jun-20 by Adam Solomon

In theory, digital retargeting should be more versatile than direct mail because it not only works for demand generation but it also enables you to send reminders. The problem with digital retargeting technology, however, is that it is enabled immediately so that the moment you leave a site after looking at, say, a pair of shoes, those shoes start following you around the internet. It’s not really a reminder to buy shoes if you haven’t had enough time to forget that you looked at them yet. And the doggedness of the pursuit can be intrusive and annoying.

A Programmatic Direct Mail® reminder hits the sweet spot: It arrives a couple of days after the online activity — just long enough to spark an “Oh, yeah — I meant to follow up on that” response. And, again, the tangibility helps the consumer. For one thing, you can take that piece of direct mail to the store with you. And if you’re not ready to go to the store just yet, you can put a Programmatic Direct Mail® reminder on the fridge or add it to your “to-do” stack. This is especially effective for brands like credit card or insurance companies where promotional codes and discount offers would be inappropriate.