Summary
/etc/squirrelmail/config.php を編集#$squirrelmail_default_language = 'en_US';
$squirrelmail_default_language = 'ja_JP';
#$default_charset = 'iso-8859-1';
$default_charset = 'iso-2022-jp';Reference
Webmailシステム構築(SquirrelMail) - Fedoraで自宅サーバー構築http://fedorasrv.com/squirrelmail.shtml