Proton Mail has today announced the rollout of post-quantum encryption (PQC) across its email platform, making quantum-resistant key generation available to all users, including those on free plans, in what the company describes as a proactive step ahead of the quantum computing era.
The feature, which users can opt into via Proton Mail’s encryption key settings, allows the generation of post-quantum-ready keys for newly sent encrypted emails. Proton’s existing encryption standards, RSA and Elliptic Curve Cryptography (ECC), remain in place and are not being replaced; PQC is an additional layer of protection applied to emails going forward.
The ‘harvest now, decrypt later’ threat
The announcement comes as security professionals increasingly warn about so-called ‘harvest now, decrypt later’ attacks, a strategy in which adversaries collect encrypted communications today with the intention of decrypting them once sufficiently powerful quantum computers become available. While no quantum computer is yet capable of breaking current public-key encryption schemes, the concern is that long-lived sensitive data, such as government communications, legal documents, and medical records, could be compromised retrospectively.
Proton has framed the move as part of a broader industry shift. NIST finalised its first post-quantum cryptography standards in 2024, and governments in several jurisdictions have begun mandating transitions for public sector agencies. Consumer-facing platforms, however, have been slower to act, making Proton’s rollout a notable milestone.
OpenPGP v6 and cross-provider interoperability
Alongside PQC support, Proton Mail is introducing compatibility with OpenPGP v6, the updated cryptographic framework that enables support for modern algorithms, including post-quantum methods. The company says it is also collaborating with the open email ecosystem, including projects such as Thunderbird, to ensure quantum-safe encrypted email can operate across providers, not just within Proton’s own infrastructure.
That interoperability focus is significant. End-to-end encrypted email has historically been hampered by fragmented adoption of standards, limiting its practical use across platforms. Proton’s involvement in cross-provider PQC standardisation efforts could help accelerate wider uptake.
Available now, including on free accounts
PQC protection is available immediately to Proton Mail’s user base, which exceeds 100 million accounts globally, across all subscription tiers. Users can enable the feature through their encryption key settings, after which newly sent encrypted emails will use quantum-resistant keys. Existing emails in the inbox are not retroactively re-encrypted, though Proton has indicated this may be addressed in future updates.
The decision to offer the feature at no additional cost, rather than restricting it to paid or enterprise tiers, is a deliberate positioning choice and one that distinguishes Proton’s approach from many enterprise security vendors, for whom advanced cryptographic features carry a premium.
A proactive posture in a shifting landscape
Proton’s timing reflects a wider reckoning in the security industry. The most consequential infrastructure transitions tend to begin well before a threat is widely understood by the public and well before organisations that delay can catch up. The standards are now set. Government mandates are accelerating. What today’s announcement signals is that quantum-safe email is no longer a theoretical ambition: it is, for Proton’s users at least, a present-day option.
