That is concerning:
As it's a simple (and cheap) IT and HR issue to set up a closed e-mail for every member of staff, even when the number of staff is in the millions.
Most private companies, including those that employ hundreds of thousands of people, have a unique e-mail address for every employee and contractor.
That is where your paycheck gets sent to, its how HR contact you, and how you send and receive all work related messages.
In the (largish, but tiny by NHS standards) company I work for, everyone from the bog cleaner to the CEO has a company ID and e-mail address, and you can not even do a afternoon of work experience from school without getting one.
HR get a load of details from every person. Even someone only doing a few hours contract work.
It includes all the usual stuff like your full name, address, bank details, NI codes and a copy of your passport.
They also take a mug shot photo and get a basic medical history.
Anyone unable or unwilling to provide all the information (and there have been a few) simply does not gain entry or get paid until they do (or don't).
(It does mean that there have been a couple of (British) contract cleaners with no passport or bank detail can not be employed)