The cookie-less mode is standard.
etracker Optimiser uses the session token procedure for this purpose, as used by etracker Analytics. This makes it possible to link back-end testing targets with the display of test variants. This means that no cookies are needed to evaluate the success of A/B tests or smart messaging.
Technically essential session cookies are only used in smart messaging campaigns to ensure that users are shown overlays at the right time during a visit and not repeatedly.