Hays, the services group turning itself into a pure staff recruitment business, has put its profitable mail operations up for sale in a move bound to attract big European players such as Deutsche Post. The 20-year-old business, which made £16.3m operating profit in the first half on £65.5m turnover, is being put on the block at a time when German, Dutch and other operators are taking advantage of the phased liberalisation of Britain's postal market to make substantial inroads into Royal Mail's 300-year-old monopoly.