The mailers, designed by Acuity, have gone out to 120,000 potential customers with a further 80,000 going to dealerships.
Smartphone users will be able to activate the digital watermark using a special app, developed by Digital Space.
Once the app is triggered, customers will be invited to call their local dealership, book a test drive, order a brochure, request a call back from their local dealer or register for dealership events.
Nearly 200 variants of the mailer will be sent, depending on the recipient, and personalised for dealers and specific DS models.
Jules Tilstone, marketing director, Citroen UK said: "Acuity's latest idea to create an engaging experience that bridges the gap between print and online, is just one in a long line of innovative ideas they have presented to us since we started working together".
Peter Cronin, managing director of Acuity said: "Most non-premium automotive brands are trying to move their products 'up-market' in attempts to increase margins. Brands in this space are particularly keen to engage with customers and build themselves into a lifestyle.
"Social media is particularly topical, as well as emerging technologies and apps. However, print is still a default method of communicating with customers en masse.
In spite of the unprecedented levels of personalisation now achievable by digital print, the vast majority of direct mail still follows a fairly generic model of a standard print piece, possibly personalised with a dealer's details. This represented an opportunity for Citroen UK to stand out from its competitors."
The campaign was developed with CRM agency The Listening Company.
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