md5

    /**
     * genero MD5 da una stringa
     * @param value stringa di origine
     * @return stringa md5 di destinazione
     */
    public static String MD5(String value) {
        try {
            java.security.MessageDigest md = java.security.MessageDigest.getInstance("MD5");
            byte[] array = md.digest(value.getBytes());
            StringBuffer sb = new StringBuffer();
            for (int i = 0; i < array.length; ++i) {
                sb.append(Integer.toHexString((array[i] & 0xFF) | 0x100), 1, 3);
            }
            return sb.toString();
        } catch (java.security.NoSuchAlgorithmException e) {
        }
        return null;
    }
    
    
    public void TestMd5() {
        MD5(sender + '|' + String.join("|", recipients) + '|' + String.valueOf(dateTime) + '|' + subject).toLowerCase();
    }