DHL Worldwide Express said Nov. 1 that its Canadian subsidiary is purchasing Mayne Group Canada Inc., a Canadian express delivery company. The purchase will, if approved by Canadian regulatory officials, make DHL Canada the third largest express delivery company in the country. The purchase is scheduled to be finished by Jan. 31, 2003, the company said. Mayne Group is better known by its brand name, Mayne Logistics Loomis. It is the Canadian arm of May Group Ltd., an Australian health care and logistics provider.