Howrah–Mumbai CSMT Mail (via Gaya)

The 12321 / 12322 Howrah–Mumbai CSMT Mail (via Gaya) also known as Imperial Indian Mail during the pre-independence era, is a daily train running between two metro cities Kolkata, (Howrah station) in West Bengal and Mumbai CSMT in Maharashtra. Numbered 12321/12322, the train belongs to the Mail category and is operated by Eastern Railway zone.

Traction
It is hauled by a Howrah Loco Shed based WAP-7 electric locomotive on its entire journey.

Route & halts
This train runs from Howrah via Barddhaman Junction, Asansol Junction, Dhanbad Junction, Gomoh Junction, Gaya Junction, Pt. Deen Dayal Upadhyaya Junction, Prayagraj Chheoki Junction, Katni Junction, Gadarwara, Itarsi Junction, Khandwa, Bhusaval Junction, Manmad Junction, and Kalyan Junction, to Mumbai CSMT.

History
Kolkata Mail as it is known now is one of the oldest train of Indian Railways with service of 150 years. This train was started by the British Indian Government on 1 June 1867 and was operated by the Great Indian Peninsular Railway. At that time this train was known as the Imperial Indian Mail and use to carry British officers, civil servants, diplomats and their family members from the then Bombay to Calcutta. At that time it was one of the most luxurious train of British India and the world. Later on after independence the name was changed to Bombay Mail, which then subsequently changed to Mumbai Mail after rechristening Bombay to Mumbai. Being a very popular train, Indian Railways has to start another train by the same name but via Nagpur. Later on to avoid confusion, Indian Railways changed its name to Kolkata Mail.