(PHP 4 >= 4.0.6, PHP 5)
mb_language — Set/Get current language
languageUsed for encoding e-mail messages. Valid languages are "Japanese", "ja","English","en" and "uni" (UTF-8). mb_send_mail() uses this setting to encode e-mail.
Language and its setting is ISO-2022-JP/Base64 for Japanese, UTF-8/Base64 for uni, ISO-8859-1/quoted printable for English.
   If language is set and
   language is valid, it returns
   TRUE. Otherwise, it returns FALSE. 
   When language is omitted, it returns the language
   name as a string. If no language is set previously, it then returns
   FALSE.