Once the Mail designated for external distribution has been weighed and franked, it often needs to be correlated into First and Second Class sub-groups, or by designated couriers, prior to departure. Sack holders hold open the sacks, allowing them to be filled whilst still mobile, avoiding the need for a continuous lifting and opening action by operatives. These units can be manufactured in single units, double units or multiple groups – in-line or back-to-back – depending on the size of the mail requirement.

Once the sacks are ready for distribution, or filled up during the day, they may need to be transferred to larger containers prior to collection. Standard or York Roll containers, designed specifically for Royal Mail letter trays, are a size that can be loaded directly onto postal or courier vans, or simply assist in the movement of multiple bags without disturbing the document flow into mail sacks held in sack holders.