Security

Your emails, your eyes only

tylloo uses end-to-end encryption (E2EE) to protect your data. When your emails are processed, the resulting drafts and classifications are encrypted on your device before being stored — and only you can decrypt them.

Once stored, we cannot read your emails. Not our engineers, not our admins, not anyone. Even if our servers were compromised, your stored data would remain unreadable.

E2EE is set up when you first use tylloo. You can choose to continue without encryption, but we strongly recommend enabling it.

How it works

When a new email arrives, tylloo processes it to classify it and generate a draft reply. Once processing is complete, the result is encrypted in your browser using your personal encryption key before it is stored on our servers. Your passphrase protects this key, and it never leaves your device.

Your passphrase never leaves your device. We don't know it, we don't store it, and we can't reset it. If you forget it, you can use a one-time recovery key that is generated during setup.

Multiple devices

When you open tylloo on a new device, you'll be asked to enter your passphrase (or recovery key). This unlocks your encryption key on that device, and your emails become readable again. The process takes a few seconds.

What this means in practice

Server breach: An attacker who gains access to our database sees only encrypted blobs. Without your passphrase, the data is useless.
Legal requests: If compelled to hand over data, we can only provide encrypted content that we cannot decrypt.
Insider threat: No tylloo employee can read your emails, regardless of their access level.
No backdoors: There is no master key, no admin override, no way for us to bypass the encryption.

Infrastructure & data residency

All servers are hosted in the European Union with providers that maintain SOC 2 and ISO 27001 certifications.
AI processing stays in the EU. All classification and draft generation is routed through AWS Bedrock in the EU. Your email content never leaves the European Union for AI processing.
All network traffic uses TLS 1.2+ encryption.
OAuth tokens for both Gmail and Microsoft 365 are encrypted at rest and scoped to minimum required permissions.
We don't use analytics, advertising, or tracking cookies.

What we don't encrypt end-to-end

To provide core functionality, a small amount of metadata remains accessible to the server:

Email category labels (e.g. "Newsletter", "Calendar Invite") — used to organise your inbox and apply labels.
OAuth connection tokens — required to read new emails from your email provider (Google or Microsoft).
Draft status (sent, pending, skipped) — used for the dashboard.

Actual email content — subject lines, bodies, recipients, and attachment metadata — is always end-to-end encrypted.

E2EE limitations worth knowing about

End-to-end encryption is a strong protection, but it has boundaries. Here is what it does and does not cover.

Server sees plaintext during processing — When a new email arrives, it is processed server-side before encryption: this is when classification and AI draft generation happen. E2EE protects your data at rest — once processing is complete, the result is encrypted in your browser before being stored. During the processing window, email content is transiently handled on our servers and is not yet encrypted. The strong guarantees described above apply after that point.
Local browser cache — Decrypted drafts are cached locally in your browser so that search and navigation feel instant. This cache is encrypted at rest with a key derived from your encryption key, so the data stored in the browser is not readable without your passphrase.
Browser security boundary — E2EE protects against server-side compromise. It does not protect against a compromised browser, for example a malicious browser extension that has full page access. We mitigate this with a strict Content Security Policy that blocks all inline scripts and restricts third-party code, but the browser itself remains a trust boundary you control.
AI processing via AWS Bedrock (EU) — Classification and draft generation send email content to Anthropic Claude models hosted on AWS Bedrock in the EU. The daily digest feature also sends email metadata — such as subjects, senders, and previews — for summarisation. All AI processing happens within the EU. Data is processed transiently and is not stored by the infrastructure provider.

Multiple email accounts

You can link multiple email accounts — both Gmail and Microsoft 365 — to a single tylloo profile. Each mailbox's data is independently scoped: classifications, drafts, and cached content are isolated per account. Access is verified separately for each connected mailbox, so linking one account never grants access to another.

Open questions?

We believe security claims should be verifiable, not just marketing. If you have questions about our encryption implementation, reach out at hello@tylloo.com.