You should go to the post office when using nonstandard envelopes or postcards. The Express Mail Service is provided by Korea Post under special agreements with the postal authorities of other countries.
The service will deliver your urgent letters, documents and parcels to another country by the safest available method.

• Please attach a sheet containing the following information on the wrap of the mail: the names, addresses, and phone numbers of the sender and the recipient; a description of the contents, their value and quantity.
• Postage charges vary, depending on the type and weight of the contents. Please consult the Korea Post home page or a post office in your neighborhood for more details.
• Concerning the status of delivery of your international postal express mail (EMS) and registered mail, please check it with the Korea Post Call Center.
• Post Office Call Center
  • General inquiries: +82-2-1588-1300 (Mon–Fri: 9 AM–6 PM; Sat: 9 AM–1 PM)