function check (form) {
	if (!form.thename.value) {
		alert ('Please give your name.');
		form.thename.focus();
		return false;
	}
	if (!form.phone.value) {
		alert ('Please give your phone number.');
		form.phone.focus();
		return false;
	}
	if (!isEmail (form.email.value)) {
		alert ('Please give a valid email address.');
		form.email.focus();
		return false;
	}
	return true;
}

function isEmail (str) {
	if (!str) {
		return false;
	}

	var iChars = '*|,"<:>[]{}`\';()&$#%';
	for (var i = 0; i < str.length; i++) {
		if (iChars.indexOf(str.charAt(i)) != -1) {
			return false;
		}
	}
	
	var iAt = str.indexOf('@');
	var jAt = str.indexOf('@', iAt + 1);
	var iDot = str.lastIndexOf('.');
	if (iAt < 1 || jAt != -1 || iDot > str.length - 3 || iDot - iAt < 2) {
		return false;
	}
	
	return true;
}