When the Chinese government cut off direct access to Gmail in June, Internet users responded by using Gmail third-party clients.
That route, though, was blocked this weekend when the Chinese government closed a gap in its Great Firewall.
However, there is still a way for Chinese Internet users to access Gmail by using software commonly known as VPNs or "virtual private networks."
VPNs can get around China's firewall because they let users access private networks. These networks are hard to censor because they prevent authorities from viewing a user's Internet activity. The Chinese government's firewall won't know when users are accessing a blocked site such as Gmail.
Many foreign companies operating in China use Gmail for their communication and will have to provide employees with VPN software to continue using Gmail.
The Chinese government first began disrupting Gmail in June, around the time of the 25th anniversary of the bloody crackdown on pro-democracy protesters in Tiananmen Square. The so-called Tiananmen Square massacre cost the lives of as many as 2,600 people according to Tiananmen Square, 1989: The Declassified History, a report published by George Washington University.
On June 3, the Chinese government blocked access to Google search, Gmail, Google Calendar and other services apparently in an attempt to blunt discussion of the 1989 pro-democracy protests. At the time, William Nee, a China researcher at Amnesty International, argued that Chinese President Xi Jinping was using the anniversary to increase Internet censorship.
Some Chinese citizens were able to access Gmail via Hong Kong IP addresses. But those IP addresses were blocked last week, Earl Zmijewski, vice president of data analytics for Dyn Research, an Internet analysis company, told Mashable.
The Google chart below shows that access to Gmail in China began to drop sharply on Dec. 25.