Sipher AI is the set of AI features inside SipherMail. This post says what they do, where they run, how to turn them off, and what we are not claiming.
Where it runs#
Sipher AI uses a language model hosted on SipherMail’s own servers in the EU. Your mail is not sent to a third-party AI provider such as OpenAI, Anthropic or Google. One model serves all the features, and a separate embedding model handles search-style lookups across your mail.
This answers where the text goes. It does not mean the AI is private in every sense. When you use an AI feature, our servers read the text that feature needs, because that is how it works. If you would rather they did not, see privacy mode below.
What the features do#
| Feature | What it does |
|---|---|
| Rewrite | Improves, shortens, expands or fixes the grammar of text you select, in a tone you choose |
| Autocomplete | Suggests ghost text as you type a draft, accepted with Tab (web) |
| Reply suggestions | Offers a few short replies to a thread |
| Auto-draft | Writes a full reply draft from the thread, in modes such as reply, concise or detailed (web) |
| Thread and message summaries | Turns a long thread or a single message into a few bullet points |
| Copilot | A chat assistant for your inbox: ask questions, find messages, summarise, draft |
| Follow-up detection | Flags threads where you owe a reply or are waiting on someone (web) |
| Label suggestions | Suggests labels based on ones you applied before (web) |
| Security check | Looks at a message you open for signs of spoofing or phishing |
| Translate | Translates a message |
| Calendar help | Pulls meeting details out of a thread and prepares an event |
Some features are web-only for now, and the phone apps are getting more. If a feature is missing in an app, check the web first.
Two wording points. The security check runs when you check a message. We do not say every message is scanned for scams. Review what the AI proposes before you send it or act on it.
Memories#
Sipher AI can keep memories, short notes about your preferences and recurring contacts that make replies more relevant. They are stored on SipherMail servers, you can view them, and you can clear them. See the memories guide.
Privacy mode#
Privacy mode turns off all Sipher AI features. When it is on, AI requests are refused. It is one switch, and it covers every feature in the table above.
Use it if you want your mailbox to behave like a plain mailbox. Turning it off again brings the features back.
Allow inbox read#
Copilot can search your inbox to answer questions. The allow inbox read preference controls that. With it on, Copilot can look through your mail for context. With it off, Copilot is not meant to read your inbox to answer.
Credits, conceptually#
AI features use credits. Each plan includes a monthly allowance, and different actions cost different amounts: a quick rewrite costs less than a long summary, for example. You can check your balance in the AI settings. We are not listing numbers here because they change, and the pricing page and the credits guide are where current figures live.
What we do not claim#
- We do not claim AI has no access to your ordinary mail. If you use a feature on a message, the server reads that message to run it.
- We do not make claims about AI and end-to-end encrypted messages in this post. Those are covered in the encryption post and the security docs.
- We do not claim the AI is always right. Summaries can miss detail, drafts can be wrong in tone, and security checks can be mistaken in either direction. Read before you send.
- We do not claim a guarantee of safe use. Do not paste secrets into a chat just because it runs on our servers.
How to choose#
If you want help with email and are comfortable with our servers processing the text you choose to send them, use the features you like and leave the rest. If you want none of it, turn on privacy mode. If you want Copilot but not inbox-wide search, leave Copilot on and switch off allow inbox read.
You can change these settings whenever you like.
For the full picture of privacy and AI, read AI privacy.