End-to-end encrypted mail stays private, even from us.
In Privacy mode, mail to other Privacy mode users is end-to-end encrypted automatically. It is locked on your device and we only store the locked copy.
How a message travels
Follow one message from your device to theirs.
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Your device locks it
Your browser or app encrypts the message and its attachments with OpenPGP before anything is sent.
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Our servers store the locked copy
We hold only the locked copy of the message and its attachments, and no key that opens it. The subject line and the addresses are not locked.
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Their device opens it
Each recipient opens it with their own key. This happens automatically when everyone on the message is a SipherMail user in Privacy mode.
Illustrative, with demo content.
Private links for people not on SipherMail.
Send a link that expires. Add a password for extra protection, and share the password another way, like a call or a text.
Link expires after
What can SipherMail see?
We won’t tell you we can’t read any of your mail. That is only true for end-to-end encrypted mail, and it depends on the mode you choose. Here is the honest picture.
| Type of mail | How it is protected | Can SipherMail read it? |
|---|---|---|
| Mail between SipherMail users who are all in Privacy mode | End-to-end encrypted automatically. Locked on the sender’s device. Only the people on the message can open it. | No |
| Mail of accounts in AI mode | Not end-to-end encrypted by default, so the assistant can work on it. The assistant runs on our own servers. | Technically yes |
| Expiring link to someone outside SipherMail, with a password | The recipient opens a link and enters the password you shared. | No |
| Expiring link, without a password | Anyone with the link can open it until it expires. | Technically yes |
| Mail from other services, and ordinary mail you send to them | Encrypted in transit, like standard email. You can choose to encrypt to someone who has an OpenPGP key. | Technically yes |
| Subject lines, addresses, dates and sizes | Never end-to-end encrypted, on any message. Mail servers need them to deliver mail. | Yes |
| Your encryption key | Locked with your passphrase before it is stored. The recovery phrase is the only other way to open it. | No |
Under the lid
What we can see
Mail to and from other services, and all mail of accounts in AI mode, is stored readable to our systems, like standard email. It is encrypted in transit. Subject lines, addresses and dates are never end-to-end encrypted.
Links that expire
For people without SipherMail, send a link that expires after 1 hour, 1 day, 1 week or 4 weeks. Add a password and we can’t read the message. Without one, anyone with the link can open it.
Your keys stay protected
Your private key is locked before it is stored, using a passphrase on the web or a key in your phone’s secure storage. We can’t unlock it. We use 310,000 rounds of hashing (PBKDF2) so guessing a passphrase is very slow.
An open standard
Encrypted mail uses OpenPGP, an open standard. You can also choose to encrypt to people at other providers who have an OpenPGP key.
Hosted in Europe
Our own servers, run by us. European privacy law (GDPR) applies, and business customers can request a data processing agreement.
AI you can switch off
Sipher AI runs on servers we operate, not at an outside AI provider. Privacy mode turns every AI feature off for your account. We don’t show ads or sell your data.
Safe sign-in
Two-step sign-in with an authenticator app, backup codes, and the option to sign out your other devices remotely.
Quiet notifications
A new-mail push carries no sender, subject or message text. The app fetches the message itself after the push arrives.
Scams spotted early
Check a message for fake senders and risky links. Known tracking pixels are removed, and images load through our privacy proxy.
Your data stays yours
Export mail, contacts and settings in standard formats. Ask us to delete your account and it is scheduled for removal after 30 days. You can change your mind until then.
Free to leave
Use SipherMail inside other mail apps, and take your mail with you any time.
Found a vulnerability?
Open a support ticket from inside the app and we’ll respond privately.