One of the benefits of Web-based e-mail is the ability to log on from just about anywhere - at home, at work, a friend's house, a mobile device or even a public library or cybercafe.
But what if you forget to log off? Someone else who encounters an active session not only can read your personal correspondences, but they also can use that account to grab your passwords from many online servicesthat offer to send reminders via e-mail.
Google Inc.'s Gmail service is trying to address that by letting you know if you're still logged on elsewhere and giving you a chance to disconnect remotely.
At the bottom of a Gmail inbox is a small notice of other active sessions. The new feature, being rolled out to users in waves, also offers some information on the time and location of recent Gmail activities.

The notification is bound to be useful, though it's by no means foolproof. You have to be logged on somewhere to learn of other active sessions, and you have to look carefully for that notice. And if you have chosen to save your password on the other computer, someone else can simply log back on unless you change it.
But the feature does offer an extra level of comfort.
"Usually I remember to sign out, but every once in a while I wonder if I really did," Gmail engineer Erwin D'Souza wrote on a company blog. "Now I no longer have to wonder."
Other major Web e-mail providers - Yahoo Inc., Microsoft Corp.'s Hotmail, Time Warner Inc.'s AOL - also allow simultaneous sessions, but they do not provide similar notice or ability to remotely log off. However, AOL does have a setting forcing automatic logoff after as little as 30 minutes of inactivity. Microsoft said Hotmail will ask for a password if the session remains idle for too long.