Sending parcels to and from Northern Ireland Find out how to move goods, in parcels or large letters, between Great Britain and Northern Ireland using the Royal Mail Group or an express carrier. From: Contents Royal Mail Group (RMG) is the UK’s designated Universal Postal Union Provider. An express carrier is a company that delivers parcels (express consignments) within a set timeframe, offering a door to door collection and delivery service. It may include: express couriers Temporary arrangements for moving goods from Great Britain to Northern Ireland HMRC has adopted a temporary approach to applying declaration requirements for the movement of goods in parcels (including by the Royal Mail Group and express carriers).