MONTREAL— Royal Mail of Britain has bought Canadian courier Dicom expanded its North American reach. Dicom with head office in Montreal and is in the parcel delivery and freight business in Canada and the US. Dicom has about over 100 remittals in North America. With more postal business moving from letter mail to parcels, a number of post office have been buying up parcel delivery companies.   DHL Courier is owned by the German Post Office. Purolator Courier is owned by Canada Post. Dicom was owned by private equity firm Wind Point Partners and was sold for around $360 million.