"Our web servers seem more busy than normal," he said.
Berlin-based email provider Posteo claims to have seen a 150 percent surge in paid subscribers due to the "Snowden effect."
Posteo demands no personal information, doesn't store metadata, ensures server-to-server encryption of messages and even allows customers to pay anonymously — cash in brown envelopes-style.
CEO Patrick Loehr, who responded to The Associated Press by encrypted email, said that subscriptions to the 1 euro ($1.36) per month program rose to 25,000 in the past four months. The company is hoping to offer an English-language service next year.
Federation of American Scientists secrecy expert Steven Aftergood said it is crucial now for policymakers to clearly define limits.