Utilize the input text as a context reference, choose the right relationship between Whistl and Mail from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

But thanks to the exit of City Link last year, and Whistl closing its letters division more recently, Royal Mail now has a clear run on the UK market, while its GLS operations overseas are also paying off handsomely.

Answer: industry