The Imperial Indian Mail was inaugurated in 1926 by the East Indian Railway (EIR) and the Grand Indian Peninsular Railway (GIPR) between Bombay (Victoria Terminus) and Howrah (for Calcutta). It was one of the most luxurious services of its time from Bombay to Calcutta. The train left Bombay every Friday with 32 passengers and the 'mail' from Britain which arrived by sea at the Bombay port. The train covered the distance at an average speed of 60 km/br, had first class facilities for passengers and could be compared to the best in the world. This later became the forerunner of the Calcutta Mails train services between Bombay and Calcutta.

The train at Bombay (Ballard Pier Mole Station) connected with the P&O steamships from Britain. In the days of the British Raj, this station was a major hub on the GIPR for the British officials arriving from Britain for the posting in colonial British India. From there they could board connecting trains to various parts of British India including New Delhi, the Punjab and Calcutta.