function checkIP() {

if (document.form.ip.value=="203.158.221.227" || document.form.ip.value=="85.47.180.91" || document.form.ip.value=="192.192.35.235" || document.form.ip.value=="193.37.152.250") {
alert("Indirizzo Email non valido.\nThe email address is not valid."); focus(); return false
}

if (document.form.Email.value=="Dan1oo@yandex.ru" || document.form.Email.value=="Dan1oo@ya.ru" || document.form.Email.value=="Dan1oo@narod.ru") {
alert("Indirizzo Email non valido.\nThe email address is not valid."); focus(); return false
}

if (document.form.Email.value!="") {
if (document.form.Email.value.indexOf("@ya.ru")!=-1 || document.form.Email.value.indexOf("@yandex.ru")!=-1 || document.form.Email.value.indexOf("@narod.ru")!=-1 || document.form.Email.value.length<6) {
alert("Indirizzo Email non valido.\nThe email address is not valid.");document.form.Email.focus(); return false
}

if (document.form.Email.value.indexOf(".com")!=-1 && (document.form.Email.value.length==17 || document.form.Email.value.length==21)) {
alert("Indirizzo Email non valido.\nThe email address is not valid.");document.form.Email.focus(); return false
}
}

}