code: public void setMailDefaultCharset(String charset) throws PageException {
  	checkWriteAccess();
  	boolean hasAccess = ConfigWebUtil.hasAccess(config, SecurityManager.TYPE_MAIL);
  	if (!hasAccess) throw new SecurityException("no access to update mail server settings");
  
  	if (!StringUtil.isEmpty(charset)) {
  	    try {
  		IOUtil.checkEncoding(charset);
  	    }
  	    catch (IOException e) {
  		throw Caster.toPageException(e);
  	    }
  	}
  
  	Element mail = _getRootElement("mail");
  	mail.setAttribute("default-encoding", charset);
  	// config.setMailDefaultEncoding(charset);
      }
docs: sets the charset for the mail
  
  @param charset
  @throws SecurityException