SipherMail is an email service built around one idea: you should be able to choose how private your mail is, and be told plainly what each choice does and does not cover. It is made by Sipher Ltd, a UK company, and it is live on the web, iPhone and Android.
This post is a short tour of what it is and who it is for.
What you get#
A normal mailbox. You get an address, an inbox, folders, labels, search, scheduled send, templates and a calendar. You can send to and receive from anyone, on any service. Third-party mail apps can connect too, over IMAP and SMTP with an app password.
End-to-end encryption you can switch on. When you write to someone who also has SipherMail encryption keys, you can send an encrypted message. The message body is encrypted in your browser or app before it leaves, and the server stores only ciphertext. We explain exactly how in a separate post.
An AI assistant on our own servers. Sipher AI can summarise threads, rewrite your drafts, suggest replies and answer questions about your mail. It runs on a model hosted on SipherMail’s own servers, not on a third-party AI provider. If you do not want AI near your mail, privacy mode turns all of it off. Details are in what Sipher AI does with your mail.
Apps everywhere. There is a web app, an iOS app and an Android app. Some newer features, such as smart categories and the offline-first cache, arrive on the phone apps with app version 1.6.
A way in from Gmail and Outlook. You can import your existing mail by signing in on Google’s or Microsoft’s own page, or from any other service with IMAP details. Your old account is never changed. See moving from Gmail or Outlook.
Personal and business plans. Individuals can start on a free account. Businesses can bring their own domain, share inboxes and manage a team. Plans and limits change, so the pricing page is the place to check them.
What "private" means here#
We want to be precise, because email privacy is easy to oversell.
- Most email is not end-to-end encrypted, and that is true of email as a whole, not only SipherMail. Mail you receive from other services, and normal messages you send, can be read by the mail server. That is how search, spam filtering and AI features work on them.
- End-to-end encryption in SipherMail is an option for specific messages between people who both have SipherMail keys. Encrypted messages are the ones the server cannot read.
- We remove known tracking pixels from incoming mail and load remote images through our own proxy. That reduces what senders learn about you. It does not stop all tracking. See tracking pixels.
- Our mail server is Stalwart, running on dedicated servers in the EU. Traffic is encrypted in transit with TLS. More in why we run on Stalwart and JMAP.
We do not use the phrase "zero-knowledge" because it would not be accurate. The server stores your encrypted private key, and it can read ordinary mail.
Who it is for#
SipherMail is for people who want a private-leaning mailbox without giving up the things they expect from a modern one: fast search, good apps, a calendar, useful AI when they want it.
It suits you if:
- You want to send some messages that even your mail provider cannot read, and are happy to use a passphrase for that.
- You like AI help with email but would rather it did not run on someone else’s AI service.
- You are leaving Gmail or Outlook and want to bring your history with you.
- You run a small business and want your own domain, shared inboxes and a simple team setup.
It may not suit you if you need every message to be end-to-end encrypted with every correspondent. That is not how email between different services works, and we would rather say so than imply otherwise.
How to start#
Create an account, import your old mail if you want to, and install the app on your phone. If you want to try encryption, set it up in Settings > Encryption on the web and pick a passphrase you will remember. On the web, that passphrase cannot be recovered by us or reset, unlike your login password. The mobile apps can set this up for you and give you a recovery code to keep safe.
If something goes wrong, open Settings > Support on the web or Settings > Help & Support in the mobile apps and send us a ticket. Service status is on our status page.
We will keep writing about how SipherMail works, including the parts that are still limited. If we claim something, we want you to be able to check it.
Start with the getting started guide.