Here is the list of Postal Service websites of each country.
 
Australian Postal Service - http://www.auspost.com.au
United States of America - http://www.usps.com
Indian Postal Service - http://www.indiapost.gov.in
Japan Postal Service - http://www.japanpost.jp
UK Postal Service - http://www.royalmail.com
Hong Kong Post - http://www.hongkongpost.com