function blank(element,value) {
    if (element.value == value) element.value="";
}

function IsEmailCorrect(email) {
  return email.match(/^[_a-zA-Z0-9-]+(\.[_a-zA-Z0-9-]+)*@([a-zA-Z0-9-]+\.)+([a-zA-Z]{2,4})$/)!=null;
}

function test() {
	if (!IsEmailCorrect(document.getElementById('email').value)) 
		{
			alert ('Your e-mail address is incorrect');
			return false;
		}
	return true;
}