The 15657 / 15658 Brahmaputra Mail is a daily train that connects Old Delhi with Kamakhya in Assam.

Introduced in 1972 after the construction of the rail section of the Farakka Barrage, the train originally ran as the Tinsukia Mail between Delhi Junction railway station and New Bongaigaon railway stations, with onward metre-gauge connection by a train of the same name numbered as 7Up and 8Dn to Guwahati and Tinsukia in the Indian state of Assam.

Later on, the primary maintenance was transferred to the Delhi Division of the Northern Railway and ran under the numbers 14056up by 14055 dn.

Once the pride of NFR with neon lights in its first class compartments and has eight cushioned sleeper class coaches in the 1970s, the train went to a sharp decline both in priority and facilities with conditioning of its rake worsening.

Northeast Frontier Railways decided it will be running as 15955/15956 Brahmaputra Mail from 9 December 2019.