function checkEmail() 
{
    var email = document.getElementById('txtemail');
    var filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
    if (!filter.test(email.value)) 
    {
        alert('Please provide a valid email address');
        email.focus
        return false;
    }
    
    
    
    
    var phone = document.getElementById('txtphone');
    if (phone.value == '') 
    {
        alert('Please provide a phone number');
        phone.focus
        return false;
    }
}