in virtually every major corperate scandal of the last few years. the best -laid plans of managerial miscreants have come unraveled, at least in part, when supposedly private e-mail surfaced as a key piece of evidence. at citigroup, for example, analyst jack grubman changed stock recommendations in exchange for favors from CEO sandy weill and then sent an e-mail to confirm the arrangement. investigators found that david duncan, arthur andersen's head enron auditor, had deleted incriminating e-mails shortly after the start of the justice department's investigation. after tim newington, an analyst for credit suisse first boston, refused to give in to change a clients's credit rating, an e-mail circulated on the problem of newington's troublesome integrity: "bigger issue," warned an upper manager, "is what to do about newington in general. I'm not sure he's salvageable at this point." not surprisingly, many corporations are nervous about the potential liability that employee e-mail may incur, but some entrepreneurs detect an opportunity in this same concern. a few software-development houses are busily designing programs to meet the needs of cautious corporate customers.