StreetPass Relay Points are a feature of Nintendo Zones in North America and Europe, that stores and sends players' StreetPass data. They allow players to get the StreetPass data of other players, even when the other player isn't there. The system works with Nintendo 3DS that are updated to system version 6.2.0-xU or higher.
StreetPass Relay Points work by storing StreetPass data they receive from 3DS' (system version 6.2.0-xU or higher) that are in sleep mode. They then send out the data (like the 3DS would), until the next 3DS comes and receives the data. When the data sent by the relay is received, it takes in the receiver's StreetPass data and begins sending that data instead. However, because of how it works the first person to go to the relay station will not receive StreetPass data, since it hasn't gathered any StreetPass data yet.