Post-quantum email, on by default
Post-quantum email uses encryption built to hold up against future quantum computers, so mail recorded today can’t be opened years from now. Secria Mail seals every message in your mailbox with ML-KEM-1024 and X25519 on every plan, including free. There is no setting to find and nothing to switch on.
Why it matters now
Quantum computers can’t read your email yet. Recordings of it can wait.
Most email today is protected by RSA or elliptic-curve keys. A large enough quantum computer could break both. Nobody has built one yet, but anyone can save encrypted mail now and open it later.
It is recorded today
US security agencies warn that attackers can collect encrypted data now and hold it until they can decrypt it. This is called harvest now, decrypt later.1
The standards are final
NIST published its first post-quantum standards in August 2024, with ML-KEM as the main one for encryption, and told teams to start switching “immediately.”2
The deadlines are set
The UK’s National Cyber Security Centre wants organizations fully moved to post-quantum cryptography by 2035, with the most important systems done by 2031.3
Your inbox holds years of tax forms, contracts, medical notes and passwords. That mail needs to stay private for longer than the time left before Q-Day. For the full background, read what post-quantum encryption is and why it matters for email.
Choosing quantum-safe email
Six questions to ask any “quantum-safe” email service
“Post-quantum” on a feature list can mean very different things. These are the questions that separate real protection from a checkbox.
| Ask this | Why it matters | Secria Mail |
|---|---|---|
| Is it on by default? | Some services make post-quantum protection a setting you have to find and switch on, and it only covers mail sent after you do.4 Protection you never turned on doesn’t protect you. | On from your first message. No setting. |
| Is it on the free plan? | Security that depends on what you pay leaves the people who pay least exposed. | Yes. Every plan gets the same encryption. |
| Which algorithm, at which level? | “Quantum-safe” without a named algorithm can’t be checked. ML-KEM comes in three sizes, and 1024 is the strongest.5 | ML-KEM-1024, the NIST standard. |
| Is it hybrid? | Pairing a new post-quantum algorithm with a proven classic one means an attacker has to break both. | Yes. ML-KEM-1024 together with X25519. |
| Who holds the keys? | Strong encryption means little if the provider can unlock your mailbox itself. | You. Keys are made on your device and only reach our servers encrypted. |
| Is the design published? | A written design lets experts check the claim instead of taking it on trust. | Yes, in our public whitepaper. |
Checked September 2026. Secria facts are from our Mail page and whitepaper.
How Secria does it
Quantum-safe email that feels like normal email
Your keys are made on your device
When you sign up, your phone or browser creates your keys. They only ever reach our servers encrypted, so your stored mail is sealed with keys we never hold. This is zero-access encryption.
Every message in your mailbox is sealed twice over
Messages are protected with ML-KEM-1024 and X25519 together. If one were ever broken, the other still stands.
You just write email
Folders, search, attachments and rich text work the way you expect, on the web, iPhone and Android. Tracking pixels are removed automatically, and senders never see your IP address.
Save your recovery phrase
Because only you hold your keys, you get a recovery phrase at signup. Keep it safe and you can always get back in.
Not sure what your current provider does? Check whether your email is encrypted, or see how to send an encrypted email.
Mail and VPN in one account
Post-quantum for your whole connection, too
Your inbox is one part of what gets recorded. Secria Pro adds the Secria VPN to the same account, with an ML-KEM-1024 key folded into every WireGuard session, on up to 5 devices.
One login, one bill, and post-quantum protection for your email and your browsing. See Secria VPN
The same post-quantum encryption on every plan
Paid plans add room and extras. They don’t add security, because everyone already has it.
Mail Plus
$3.99/mo
20 GB, 15 aliases, 3 custom domains, unlimited folders, breach alerts.
Get Mail PlusSecria Pro
$9.99/mo
500 GB, unlimited aliases, 10 custom domains, and the full Secria VPN on 5 devices.
Get Secria ProMonthly prices shown. Yearly and 2-year plans cost less per month. Compare all plans
30-day money-back on plans bought here. App Store and Google Play purchases follow their own refund rules.
Questions about post-quantum email
What is post-quantum email?+
Post-quantum email is email encrypted with algorithms designed to resist attacks from future quantum computers, as well as today’s computers. The main standard is ML-KEM, which NIST published as FIPS 203 in August 2024.
Is quantum-safe email the same as quantum-resistant email?+
Yes. Post-quantum, quantum-safe and quantum-resistant all describe the same thing: encryption built on math that quantum computers are not known to break. Post-quantum is the term standards bodies like NIST use.
Can a quantum computer read my email today?+
No quantum computer can break today’s email encryption yet. The risk is that encrypted mail recorded now gets stored and opened later, once such a machine exists. That is why post-quantum protection matters before that day, not after.
When will quantum computers break encryption?+
Nobody knows the exact year. Governments are not waiting to find out: the UK’s NCSC wants organizations fully moved to post-quantum cryptography by 2035, and NIST has urged teams to start switching now because the change takes years.
Do I have to turn on post-quantum encryption in Secria?+
No. It is on from your first message, on every plan, with no setting to find. Your keys are made on your device when you sign up.
Is Secria’s post-quantum encryption free?+
Yes. The free plan gets the same ML-KEM-1024 and X25519 encryption as Mail Plus and Pro. Paid plans add storage, aliases, custom domains and, with Pro, the Secria VPN. More on the free plan in free encrypted email.
What is ML-KEM-1024?+
ML-KEM is the post-quantum key exchange NIST standardized in FIPS 203. It comes in three sizes, and ML-KEM-1024 is the largest, with the highest security level of the three. Read more in our ML-KEM glossary entry.
Sources
- CISA, NSA and NIST, Quantum-readiness: migration to post-quantum cryptography (August 2023).
- NIST, NIST releases first 3 finalized post-quantum encryption standards (August 2024).
- UK National Cyber Security Centre, Timelines for migration to post-quantum cryptography (March 2025).
- Help Net Security, report on a major email provider’s opt-in post-quantum setting (May 2026).
- NIST, FIPS 203: Module-Lattice-Based Key-Encapsulation Mechanism Standard (August 2024).
Checked September 2026.
Mail that stays private after Q-Day. Free, and on from your first message.
