(AP) -- Google is tightening the security of its free e-mail service to combat computer hackers like the ones that recently targeted it in China.

With the shift, Gmail accounts will automatically be set in an "https" mode, meaning contents of e-mail will be scrambled so they're less likely to leak out to unauthorized users. Before, only the log-in data was encrypted.

Google hadn't been using this more secure format as Gmail's default setting because it can be slower than the unprotected mode.

The shift to the more secure setting began late Tuesday, just a few hours after Google announced Chinese hackers had pried into the e-mail accounts of human rights activists. Google is now considering pulling out of and shutting down its there because of the attacks.