Experts have spotted a new type of emails designed to lure unsuspecting Internet users to a phishing website. The messages purport to come from Walmart and they inform recipients of unclaimed vouchers. The emails carry the subject line Your Walmart Voucher and they read something like this: Our Walmart reward server has identified this email to have 500 dollars worth of unclaimed walmart vouchers. It has been difficult to send this vouchers to you because you have not co…