Graphic: Proton Technologies

The Turkish government is reportedly blocking the use of ProtonMail, the world’s largest encrypted email service.

In a statement Thursday, the service’s provider, Proton Technologies AG, said that it became aware of connectivity problems for Turkish users on Tuesday and has since concluded there’s no technical glitch.

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“Internet censorship in Turkey tends to be fluid so the situation is constantly evolving,” Proton said. “Sometimes ProtonMail is accessible, and sometimes it is unreachable. For the first time ever though, we have confirmed that ProtonMail was subject to a block, and could face further issues in the future.”

An inquiry to the Turkish embassy was not immediately returned.

Headquartered in Geneva and founded by a group of scientists and engineers, Proton was launched thanks to a hugely successful crowdfunding campaign in 2014. Its email service offers end-to-end encryption, relying solely on open source cryptography, and zero-access architecture, meaning its mathematically impossible for the company to examine user data. Moreover, emails transmitted using the service can be automatically destroyed.

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In other words, ProtonMail, which is free to use, is the perfect platform for journalists and dissidents—two classes of people whom the Turkish government routinely targets. Since early 2016, Turkey has been the world’s biggest jailer of journalists. Earlier this month, an Istanbul court sentenced 25 journalists to prison on terrorism-related charges.

According to ProtonMail, censorship of its platform using DNS blocking was confirmed with the assistance of Turkish users. “The type of DNS blocking that has been performed against ProtonMail very much fits the modus operandi of the Turkish government’s online censorship efforts,” the company said.

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ProtonMail offered a list of ways to bypass the censorship, which are detailed below:

Use a VPN Service: Proton Technologies offers its own free VPN service. The company warns, however, that while VPNs remain one of the best ways to bypass government censorship, they don’t always work. “It is possible to block all VPN services (and Turkey is currently attempting to ban all VPN services), in which case, there are a few other circumvention techniques,” the company said.

Change DNS servers: Since ProtonMail is being blocked at the DNS level, changing your DNS from Vodafone’s default should work. You can find a list of alternative DNS servers here. (Find instructions on how to change your DNS on Proton’s website.)

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Build a Tor Bridge: The Turkish government has been working to ban Tor, but according to Proton, “using Tor Bridges has so far still been an effective method of circumventing online censorship.” (Guides for using Tor Bridge are here and here.) Using Tor, you can access ProtonMail’s hidden service at the following address: protonirockerxow.onion

Got a tip about government censorship? Contact the reporter at dell.cameron@gizmodo.com