Chinese users of Microsoft's Outlook email service were subject to a hacking attack at the weekend, a few weeks after Google's Gmail system was blocked in China. People using email clients like Outlook, Mozilla's Thunderbird and apps on their phone with the SMTP and IMAP email protocols, which are used to send and receive messages, around Saturday were subject to a "man-in-the-middle" (MITM) attack, said Online censorship watchdog GreatFire.org. A MITM attack hijacks an online connection to monitor and sometimes control communications made through that channel.

However that the web interfaces (https://outlook.com and https://login.live.com/ ) were not affected, the China-based watchdog said. The attack lasted for about a day and has now ceased.

The attack comes within a month of the complete blocking of Gmail in China (which is still entirely inaccessible). Because of the similarity between this attack and previous, recent MITM attacks in China (on Google, Yahoo and Apple), the watchdog suspects that the Cyberspace Administration of China have orchestrated this attack or have willingly allowed the attack to happen.

This new MITM attack comes three months after an iCloud MITM attack, which was widely reported in the media and which prompted Apple’s CEO Tim Cook to fly to China to raise the matter directly with the Chinese authorities. China had denied the "hacking" allegation and Apple has not made any public statements addressing the outcome of the discussions. However Apple did add a Chinese language help page which addresses similar issues.