Two major secure email service providers on Thursday took the extraordinary step of shutting down service.

A Texas-based company called Lavabit, which was reportedly used by Edward Snowden, the former CIA computer analyst turned whistleblower, announced its suspension on Thursday afternoon, citing concerns about secret government court orders.

By evening, Silent Circle, a Maryland-based firm that counts heads of state among its customers, said it was following Lavabit’s lead and shutting its email service as a protective measure.

Taken together, the closures signal that emails, even if they are encrypted, can be accessed by government authorities and that the only way to prevent turning over the data is to obliterate the servers that the data sits on.

Mike Janke, Silent Circle’s chief executive, said in a telephone interview late Thursday that his company had destroyed its server. “Gone,” he said. “Can’t get it back. Nobody can. We thought it was better to take flak from customers than be forced to turn it over.”

The company, in a blog post-dated for Friday, said it had taken the extreme measure even though it had not received a search order from the government.

Ladar Levison, the owner of Lavabit, suggested — though did not say explicitly — that he had received a search order, and was opting to shut the service so as not to be “complicit in crimes against the American people”.

“After significant soul searching, I have decided to suspend operations,” he wrote. “I wish that I could legally share with you the events that led to my decision. I cannot. I feel you deserve to know what’s going on — the First Amendment is supposed to guarantee me the freedom to speak out in situations like this. Unfortunately, Congress has passed laws that say otherwise. As things currently stand, I cannot share my experiences over the last six weeks, even though I have twice made the appropriate requests.”

The gag order could refer to a secret court order from the Foreign Intelligence Surveillance Court or a National Security Letter. Both prohibit the recipient from saying anything about it.

Silent Circle, which has been in operation for less than a year, said it would continue its phone and text messaging service, which are encrypted end-to-end. Email, by its very nature, Janke said, “is within the reach of any government”.

“We’d considered phasing the service out, continuing service for existing customers, and a variety of other things up until today,” the company’s blog post continued. “It is always better to be safe than sorry, and with your safety we decided that the worst decision is always no decision.”

The announcements spread fast on social media, drawing praise, anxiety and donations to Lavabit’s legal defence fund.

Lavabit’s Facebook page had lit up with comments from frustrated, angry users. “please re-open the servers just that we can recover th info!!!” wrote one.

Levison described how his service worked in a lengthy post in 2009, saying that Lavabit had 140,000 users, including 70 companies. The security researcher Mikko Hypponen posted a link to his post on Twitter.

The Electronic Frontier Foundation late on Thursday reiterated its call for “more transparency” over government court orders for internet users’ information.