Collaborative last mile solutions, such as the collaborative use of parcel lockers, jointly used logistics facilities in inner city area, and white-label delivery play an increasing role to alleviate inefficiencies particularly caused by failed home delivery attempts and generated externalities associated with last mile deliveries. However, there is limited research on the impacts of collaborative delivery approaches in last mile logistics. Therefore, this paper explores the extent to which collaborative delivery solutions contribute to a more sustainable urban transport and what impacts can comparatively be observed on relevant parameters (e.g. number of trips, mileage performed, costs, emissions) in one single case study. For this purpose, a synthetic world for the City of Hamburg, Germany, has been built up focusing on the parcel market with respectively parcel service providers as well as their private and commercial customers. Based on this, a reference scenario and three collaborative distribution scenarios (e.g. white-label delivery, collaborative use of parcel stations) are developed which are simulated by the microscopic agent-based transport simulation MATSim and the integrated logistics behavior model Jsprit. Results strongly indicate that positive transport-related, economic and environmental impacts could be achieved through the implementation of collaborative delivery solutions.