Starting December 1, 2013 for the first time electronic registration became available at issuance of an electronic ticket for a ride from any station throughout the entire train route. Before, the service could be used only when boarding at stations located within four hours from route's starting station. 

The service is available on all "Federal Passenger Company’s" trains, running on Russian domestic lines except trains that are bound for Kaliningrad Oblast and back. Due to the electronic registration, prior the trip the passenger does not need any more to print out his e-ticket on a printed form at the ticket office or at self-service terminal. Regardless of the boarding station, passengers can register online not later than 1 hour before the train departures from route's starting station. To board the train throughout entire route, it is enough for the passenger to present his electronic ticket (boarding pass) printed on A4 paper or an image on mobile device's screen to the car conductor, as well as to show an ID of the passenger, whose name  is specified in e-ticket.

Sources: russia-ic