New Zealand Post says that by Christmas Eve it expects to have passed on about 100,000 letters to Santa Claus.
The letters, usually addressed to "Father Christmas, North Pole", are read by Santa's helpers before a reply is sent back.
Peter Fenton, the chief executive of postal services, says it is always interesting to find out what children want for Christmas.
Dolls are still popular with girls, he says, and the latest Playstation, PS3, is another much-requested item.
One has child asked for a nice girlfriend and a pair of socks.
In Australia, Australia Post says Christmas mail should still get through, despite threatened industrial action on Tuesday and Wednesday.
Workers were scheduled to walk off the job at midnight on Monday amid a dispute over an enterprise agreement, but Australia Post expects only a third of its workers to strike, and will have contingency plans in place to ensure mail goes through.