As space missions increase, there’s a growing need for efficient, network-centric communication to replace traditional point-to-point methods. Disruption/Delay Tolerant Networking (DTN) with the Bundle Protocol (BP) is considered as the future internetworking protocol for space, particularly in the LunaNet Interoperability Specification and for future Mars and Earth Observation missions. Given the challenges of intermittent connectivity and long delays in DTNs, reliable data transfer mechanisms are essential. This presentation will introduce a new custody transfer mechanism for Bundle Protocol Version 7 (BPv7), which will be published as an experimental specification by CCSDS in 2025. Unlike its predecessor, BPv6, which included a custody transfer mechanism, BPv7 requires a separate extension for reliable delivery. Our proposed solution introduces a) an efficient method for identifying sets of bundles using sequence numbering, b) a new Custody Transfer Extension Block with a Compressed Custody Signal for efficient reporting on custody acceptance or rejection, and c) a Compressed Reporting Extension Block with a Compressed Reporting Signal for status reporting on bundle reception, deletion, forwarding, and delivery. These mechanisms have been prototyped in ESA’s BP implementation and considered for Earth Observation, Lunar, and Mars scenarios. This talk details the design, specification, implementation, and emulation results, providing insights into future developments in DTN reliability.