function checkEmailAddress(email)
{
	var address = email.value;
	var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
	if (address != '')
	{
		if (reg.test(address) == false)
		{
			alert('Please enter a valid email address');
			return false;
		}
	}
}