The units entered into service carrying parcels and mail from London to Glasgow and Edinburgh at 100 mph (160 km/h).

Such work continued alongside Class 86 locomotives up the West Coast Main Line and East Coast Main Line until 2003, when Royal Mail withdrew the postal contracts, resulting in decreasing use until the units entered storage following the end of work.

[6] When First GBRf gained a new contract for mail transport over Christmas 2004, the Class 325s returned to limited work operating in multiple.

A new contract for Royal Mail operations, and responsibility for managing the Class 325 fleet, was won by DB Schenker.

As of June 2010[update], seven trains were to be run a day, between London, Warrington and Glasgow via the West Coast Main Line, with capacity to be flexible as required.

In 2012, unit number 325010, which had been damaged and was stored as a source of spares for the rest of the fleet, was disposed of by scrapping.