Who gets more than six million personalized letters every year? Santa Claus -- also known as Father Christmas, Saint Nicholas and Ded Moroz (Russia [Images]), according to the United Nations Universal Post Union.

Postal operations in at least 20 countries employ special elves to handle -- and respond to -- the huge volume of mail, often addressed simply 'To Santa, North Pole,' and peaking every December.

Canada [Images] Post replies to letters in 26 languages while Germany's [Images] Deutsche Post replies in 16 languages. In some countries, Santa even answers his own emails.

Many UPU members say the volume of mail continues to increase despite the emergence of emails, text messages and other forms of electronic communication in recent years. Canadians and the French are among the busiest correspondents, with more than one million children in each country sending letters each year.

The UPU reports that it is not entirely clear where Santa lives: Last year, 90 per cent of the total letters were sent to Finland, but thousands of letters were also sent from other countries to France [Images], Germany and Slovakia.

In Canada, meanwhile, Santa enjoys his own postcode: H0 H0 H0.