Setting mail header for a foreign language

Depending on the client's regional settings and an ability to read foreign language on the client's computer, emails sent using traditional text/plain mail header may not be readable by foreign receipients. To allow mails to be sent in correct format, the following mail headers must be set in addition to From, CC and BCC mail headers.

MIME-Version: 1.0
Content-Type: text/plain; charset=ks_c_5601-1987
Content-Transfer-Encoding: quoted-printable

The example above uses Korean ks_c_5601-1987 character set, but any language code will work including UTF-8.