Eighteen months or so after Google Gears debuted, a period of time scarred by several major Gmail outages, Google’s cloud-accessible-only e-mail is finally getting invested with offline support.

English-speaking US and UK Gmail users who want to test the new skill can now catch up with the rest of the world.

Google calls the feature “early experimental,” but then Gmail is still in beta two years after its general release.

Although Google has been using the widgetry internally “for quite a while,” it warns that there still may be “some kinks that haven’t been completely ironed out yet.” It’s looking for feedback.

Once the feature is turned on, Gmail uses Gears to download a local cache of the user’s mail. As long as a connection to the network is maintained, that cache is synchronized with Gmail’s servers. When Internet connection is lost, Gmail automatically switches to offline mode and uses the data stored on the user’s hard drive instead of sending the messages across the network.

Any messages a user sends while offline go to his outbox and get sent when Gmail detects a connection. There’s a “flaky connection mode” for when the user’s on an unreliable or slow connection. Google says it uses the local cache as if you were disconnected, but still synchronizes your mail with the server in the background. It’s striving for the same user experience on- and offline.