Gmail users in China are reportedly having trouble accessing Google's free email service in the region.
The shutdown was first reported by GreatFire.org, an organization that monitors online censorship in China. The site today re-tweeted a message from a Beijing-based writer who said in a translated message that Gmail was "fully blocked."
In another tweet, the writer - who goes by the name Fang - said that Gmail traffic from China has "dropped close to zero" since Dec. 27, and speculated whether email services from Yahoo or Microsoft would be next.
Google did not immediately respond to a request for comment, but told Reuters that "there's nothing wrong on our end."
Google's Transparency Report, which lets users see whether Google services are blocked in particular regions, shows a steep drop-off in Gmail access beginning mid-day on Dec. 26.
Service cut-offs in China, of course, are nothing new. In June, Google services were blocked before the 25th anniversary of the Tiananmen Square protests, Bloomberg reported. But Google products, like Gmail, have faced various blockades over the years, while search results are often censored.
Google has also tangled with China over that censorship. In 2010, Google discovered a sophisticated attack that originated in China, which was designed to steal Google intellectual property and access the Gmail accounts of Chinese human rights activists. As a result, Google said it would stop censoring its search results in China, and possibly pull out of the Chinese market altogether depending on the reaction of Chinese officials.
It later started redirecting Google.cn traffic to its Hong Kong site, Google.com/hk. But in a bid to avoid having its content provider license yanked in China, Google stopped redirecting that traffic in June 2010 in favor of a hybrid landing page.
Chinese officials have tried in vain to limit citizens' access to Google services; last year, it bemoaned the country's "serious dependence" on Google's mobile operating system, Android.
For more, check out our roundup of Gmail tips in the slideshow above.