Irvine-based Sendio, which develops email security software, has rolled out an upgraded version of the firm's email security appliance. According to Sendio, its E-Mail Security Platform (ESP) eliminates spam and thwarts viruses. The appliance uses a combination of SMTP tests and other methods to identify e-mail servers, along with sender address verification to very senders of emails to a user. The appliance--which was formerly known as the Sendio I.C.E. box--adds new features based on low-level SMTP testing to validate e-mail servers, a technology the firm has billed as "Silverlisting." The firm, which is venture backed by Kline Hawkes and Momentum Venture Management, said there are two versions of the appliance, one targeted at small and medium sized businesses, and one for enterprises.