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.

Corporate networks, which typically have several layers of defences against hackers, can require special software and multiple passwords for access. Some companies use systems that give employees a security code that changes every 60 seconds; this must be read from the display screen of a small card and typed quickly.

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. So far, no major corporate disasters caused by this kind of e-mail forwarding have come to light. But security experts say the risks are real. For example, the flimsier security defences 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.

Also, because messages sent from Web-based accounts do not pass through the corporate mail system, companies could run afoul of federal laws that require them to archive corporate mail and turn it over during litigation. Besides, companies have no control over the life span of e-mails in employees’ Web accounts. “If employees are just forwarding to their Web e-mail, we have no way to know what they are doing at the other end,” said Joe Fantuzzi, chief executive of the information security firm Workshare. “They could do anything they want. They could be giving secrets to the KGB.”

—BRAD STONE / NYT