Gmail traffic between Google's data centres is now encrypted to prevent unauthorised government snooping, the company said today.
In October last year, former National Security Agency contractor Edward Snowden leaked documents that indicated the spy agency had been tapping intra-data centre links to capture Google and Yahoo user data.
At the time, Google said it would start encrypting all its internal traffic in response to the revelations about mass government surveillance.
Google's Gmail security engineering lead Nicolas Lidzborski said the process is now complete.
"In addition, every single email message you send or receive—100 per cent of them—is encrypted while moving internally," Lidzborski said.
"This ensures that your messages are safe not only when they move between you and Gmail's servers, but also as they move between Google's data centers—something we made a top priority after last summer’s revelations."
Lidzborski also said that from today, Gmail will use encrypted Hypertext Transfer Protocol Secure (HTTPS) only, to prevent interception of email traffic.
Rival freemail provider Yahoo is also encrypting email connections by default.
Microsoft, which too featured prominently in Snowden's leaked documents, said in December last year it will embark on an aggressive cryptography campaign, using Perfect Forward Secrecy and 2048-bit cypher keys.
Data communications and user content will be encrypted fully by the end of 2014, Microsoft's general counsel Brad Smith said.