function validate_form ( )
{
    valid = true;
	
	var nameField = document.getElementById("name");
	var emailField = document.getElementById("email");
	var phoneField = document.getElementById("telephone")

    if ( nameField.value == "" )
    {
        alert ( "Please fill in your name." );
        valid = false;
    }
	emailCheck(emailField.value)
    if ( phoneField.value == "" )
    {
        alert ( "Please fill in your telephone number." );
        valid = false;
    }
	    return valid;
}
function emailCheck (emailStr) 
{
	var checkTLD=1;
	var knownDomsPat=/^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum)$/;
	var emailPat=/^(.+)@(.+)$/;
	var specialChars="\\(\\)><@,;:\\\\\\\"\\.\\[\\]";
	var validChars="\[^\\s" + specialChars + "\]";
	var quotedUser="(\"[^\"]*\")";
	var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/;
	var atom=validChars + '+';
	var word="(" + atom + "|" + quotedUser + ")";
	var userPat=new RegExp("^" + word + "(\\." + word + ")*$");
	var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$");
	var matchArray=emailStr.match(emailPat);

	if (matchArray==null) 
	{
		alert("Email address seems incorrect (check @ and .'s)");
		return valid=false;
	}

	var user=matchArray[1];
	var domain=matchArray[2];

	for (i=0; i<user.length; i++) 
	{
		if (user.charCodeAt(i)>127) 
		{
			alert("Ths email contains invalid characters.");
			return valid=false;
   		}
	}

	for (i=0; i<domain.length; i++) 
	{
		if (domain.charCodeAt(i)>127) 
		{
			alert("Ths domain name contains invalid characters.");
			return valid=false;
   		}
	}

	if (user.match(userPat)==null) 
	{
		alert("The email address doesn't seem to be valid, please correct.");
		return valid=false;
	}

	var IPArray=domain.match(ipDomainPat);

	if (IPArray!=null) 
	{

		for (var i=1;i<=4;i++) 
		{
			if (IPArray[i]>255) 
			{
				alert("Destination IP address is invalid!");
				return valid=false;
   			}
		}

		return true;
	}

	var atomPat=new RegExp("^" + atom + "$");
	var domArr=domain.split(".");
	var len=domArr.length;

	for (i=0;i<len;i++) 
	{
		if (domArr[i].search(atomPat)==-1) 
		{
			alert("The domain name does not seem to be valid.");
			return valid=false;
   		}
	}

	if (checkTLD && domArr[domArr.length-1].length!=2 && domArr[domArr.length-1].search(knownDomsPat)==-1) 
	{
		alert("The address must end in a well-known domain or two letter " + "country.");
		return valid=false;
	}

	if (len<2) 
	{
		alert("This address is missing a hostname!");
		return valid=false;
	}

	return true;
}