// JavaScript Document
function checkform()

{
var form=document.forms[0]

if (isEmail(form.Email.value) == false) 
{
        alert("Please enter a valid email address.");
        form.Email.focus();
        return false;
}

if (form.Sender.value == "") 
{
        alert("Please enter your name.");
        form.Sender.focus();
        return false;
}

if (form.Phone.value == "") 
{
        alert("Please enter your phone number.");
        form.Phone.focus();
        return false;
}

if (form.Message.value == "") 
{
        alert("Please enter your message.");
        form.Message.focus();
        return false;
}


}

function isEmail(string) 
{
    if (string.search(/^\w+((-\w+)|(\.\w+))*\@\w+((\.|-)\w+)*\.\w+$/) != -1)
        return true;
    else
    return false;
}