The amount you tip a mailman for Christmas can vary based on a number of factors, such as the level of service they have provided throughout the year and the amount of work they have done during the holiday season. Generally, a good rule of thumb is to tip 10-20% of the total bill for gifts or deliveries, or to give a cash gift of $20-$100. Additionally, a small gift of appreciation such as baked goods, a card, or a token of your appreciation is also a thoughtful gesture.