How to check the reason for return of Outward International Mail with an item number?

If a mail item is returned from overseas (with a valid address but without reason for return indicated), the sender can make an enquiry about the reason for return, provided that an item number is available. An enquiry form Pos28B should be completed and submitted with proof of mailing, and a copy of the front and back of the wrapping of the returned item to Hongkong Post:

1. By Mail to Mail Tracing Office, Hongkong Post, 12/F Kennedy Town Community Complex, 12 Rock Hill Street, Kennedy Town, Hong Kong
2. In person to any post office
3. By fax to 2543 0469

Hongkong Post will check with the overseas postal administration for the reason for return.