A growing number of Internet-literate workers are forwarding their office e-mail to free Web-accessible personal accounts offered by Google, Yahoo and other companies. Its a hole you can drive an 18-wheeler through, said Paul D. Myer, president of the security firm 8E6 Technologies in Orange, Calif. It is a battle of best intentions: productivity and convenience pitted against security and more than a little anxiety. Corporate techies who, after all, are paid to worry want strict control over internal company communications and fear that forwarding e-mail might expose proprietary secrets to prying eyes. Employees just want to get to their mail quickly, wherever they are, without leaping through too many security hoops. That is too much for some employees, especially when their computers can store the passwords for their Web-based mail, allowing them to get right down to business. For example, the flimsier security defenses of Web mail systems could allow viruses or spyware to get through, and employees could unwittingly download them at the office and infect the corporate network.