function validate_form(x)
{
	if(x.user_firstname.value == "")
	{
		alert("Please enter your first name");
		x.user_firstname.focus();
		return false;
	}
	
	if(x.user_surname.value == "")
	{
		alert("Please enter your surname");
		x.user_surname.focus();
		return false;
	}
	
	else if(x.user_phone.value == "")
	{
		alert("Please enter a telephone number");
		x.user_phone.focus();
		return false;
	}

	else if(!(isEmail(x.user_email.value)) || x.user_email.value == "")
	{
		alert("Please enter a valid email address");
		x.user_email.focus();
		return false;
	}
	
		
		else if(x.user_message.value == "")
	{
		alert("Please enter your message");
		x.user_message.focus();
		return false;
	}
		
		else if(x.security_code.value == "")
	{
		alert("Please enter the security code as shown in the image");
		x.security_code.focus();
		return false;
	}
	
}

function isEmail (theStr) 
{
	var atIndex = theStr.indexOf('@');
	var dotIndex = theStr.indexOf('.', atIndex);
	var flag = true;
	theSub = theStr.substring(0, dotIndex+1)
	if ((atIndex < 1)||(atIndex != theStr.lastIndexOf('@'))||(dotIndex < atIndex + 2)||(theStr.length <= theSub.length)) 
	{	 
		flag = false; 
	}
	else 
	{ 
		flag = true; 
	}
	return(flag);
}