EMAIL_BODY_CHARSET

(string, character set name) The character set to translate SMS text to prior to insertion into an email message’s body. If necessary, the translated text will be MIME encoded. The default value is US-ASCII. If the SMS message contains glyphs not available in the charset, they will be converted to mnemonic characters, which may or may not be meaningful to the recipient.

A list of the character sets known to the MTA may be found in the following file:

installation-directory/config/charsets.txt