Last Wednesday, Roskomsvoboda, which describes itself as “the first Russian public organization active in the field of protecting digital rights and expanding digital opportunities,” reported that an unknown Russian state organization ordered the block of Skiff, an email and cloud service provider launched last year. Since then, Skiff’s chief executive Andrew Milich shared evidence of the block with TechCrunch.

The block against Skiff comes three years after Russia blocked similar email encrypted services Proton Mail and Tutanota, showing that President Vladimir Putin’s regime is decidedly clamping down on encrypted communication services that allow its citizens to conduct conversations that are harder to spy on.

The Russian Embassy in Washington, D.C., did not respond to a request for comment. The Russian government’s censorship authority, commonly known as Roskomnadzor, also did not respond to an email asking for comment. Roskomnadzor’s register of blocked sites does not list Skiff as blocked at the time of publication.

Stanislav Shakirov, technical director and co-founder of Roskomsvoboda, told TechCrunch that the block is in full effect and that “the blocking is done by the ISP on their equipment by the URL mask (*.skiff.com) and IP addresses.”

Shakirov explained that this has the effect of blocking Skiff.com and all of its subdomains, “thus, Russian users who are not using VPN, browser plugins, or censorship bypass tools like Tor or Psiphon can’t get access to Skiff services.”

Skiff’s Milich told TechCrunch that the company has seen an 81% decrease in traffic from Russia since last week, and he also shared a video of a user in Russia trying to log on to Skiff, which ends with the user seeing a connection error. Milich added that he has received several complaints from users in Russia that the service is not usable anymore.

According to Skiff, the company has half a million users in Russia.

“I started Skiff with a more private vision for the internet, where our personal information is not shared, bought, and sold. [Skiff’s co-founder ] Jason [Ginsberg] and I have both had personal or professional connections to Russia — mine through Stanford, and Jason’s family escaped the Soviet Bloc in the late 1970s via a covert radio network,” Milich said. “With fast adoption of our products and now suppression of them, we’re even more confident and determined in our mission to build products for private communication and freedom.”