Plain-language definition
The confirmation that a message was delivered, failed or is pending.
Technical definition
In SMPP a DLR is a deliver_sm with esm_class indicating a receipt and a text body containing id, stat (DELIVRD, UNDELIV, EXPIRED) and timestamps; SMSCs derive it from MAP delivery outcomes.
Why it matters
DLRs drive quality monitoring and billing, but they confirm supplier acceptance, not handset integrity, which is why route testing exists.
Last reviewed 2026-09-12 by the Guardivia QoS Engineering Team. Product facts on this page describe current capabilities; items marked “where supported”, “optional”, “integration” or “consultancy” are confirmed per deployment.