According to factmonster--Some historians say the holiday developed because servants were required to work on Christmas Day, but took the following day off. As servants prepared to leave to visit their families, their employers would present them with gift boxes.
Church Alms Boxes
Another theory is that the boxes placed in churches where parishioners deposited coins for the poor were opened and the contents distributed on December 26, which is also the Feast of St. Stephen.
As time went by, Boxing Day gift giving expanded to include those who had rendered a service during the previous year. This tradition survives today as people give presents to tradesmen, mail carriers, doormen, porters, and others who have helped them.
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