Privacy Policy
Mostpost is a privacy-first email client. It is built so that your mail stays on your devices and under your control. This policy explains what data Mostpost handles, why, and — just as importantly — what we never do with it.
1. Who we are
Mostpost is operated by Alvorado Digital (“Mostpost”, “we”, “us”). You can reach us at support@mostpost.io.
2. Our core privacy model
- Local-first. Your email is fetched directly from your mail providers to your device and stored in an encrypted local database on that device. We do not operate a server that stores your mailbox.
- You hold the keys. Mostpost uses post-quantum hybrid encryption (ML-KEM-1024 + X25519) for its end-to-end-encrypted features. Key material is derived from a seed that never leaves your device and is never transmitted to us.
- AI runs locally or on a server you control. Inbox triage, summaries, draft suggestions, and task/event extraction run on your device or against an AI endpoint you configure and control. Encrypted message content is never sent to third-party cloud AI services.
- No advertising. No data sales. We do not sell, rent, or share your data with data brokers, and we do not use your data for advertising.
3. Information Mostpost handles
3.1 Email account data. When you connect a mailbox (Gmail, Microsoft 365, Fastmail, IMAP, etc.), Mostpost accesses — on your device — the data needed to function as an email client: message headers and bodies, threads, labels/folders, attachments, contacts/addresses, and read/unread state. This content is stored in the encrypted local database on your device and processed locally (or by your own AI server).
3.2 Authentication tokens. For OAuth providers (Google, Microsoft), Mostpost stores access/refresh tokens to maintain your session. To deliver push notifications, tokens or minimal subscription metadata may be held by a minimal-knowledge relay we operate; it holds only what is needed to wake your device on new mail and is designed not to read your message content. Tokens are stored securely (platform keychain / encrypted storage) and used only to access your own mailbox on your behalf.
3.3 Diagnostics (optional). If you opt in, Mostpost may send anonymized crash reports and performance metrics. These never contain message content, addresses, or credentials. You can disable this in Settings.
3.4 Website. mostpost.io uses basic, privacy-respecting server logs and no advertising trackers.
4. How Google user data is used (Gmail API)
When you connect a Gmail or Google Workspace account, Mostpost requests these scopes and uses them only as described:
- gmail.readonly — read your messages, threads, labels, and attachments to display your inbox and run local triage.
- gmail.send — send messages and replies that you compose and choose to send.
- gmail.modify — keep read/unread (and archive) state consistent between
Mostpost and Gmail. We request
gmail.modify, not full access; Mostpost cannot permanently delete your mail.
Google data is processed on your device or on your own AI server. It is not transferred to us except as strictly necessary to provide push notifications via the minimal-knowledge relay described above, for security, or to comply with law.
5. Limited Use (Google API Services User Data Policy)
Mostpost’s use and transfer of information received from Google APIs adheres to the Google API Services User Data Policy, including the Limited Use requirements. Specifically:
- We use Google user data only to provide and improve the user-facing features of Mostpost that you request.
- We do not transfer Google user data to others except as necessary to provide or improve user-facing features, for security purposes, or to comply with applicable law.
- We do not use Google user data for serving advertising.
- We do not allow humans to read your Google user data unless: (a) we have your specific consent for a particular message or thread; (b) it is necessary for security; (c) it is required to comply with applicable law; or (d) the data has been aggregated and anonymized.
- We do not use Google user data to develop, train, or improve generalized or non-personalized AI/ML models. Mostpost’s AI runs locally or on the user’s own server and operates only on that user’s own data to serve that user.
6. How we share data
We do not sell your data. We share data only: with your mail providers, to access your own mailbox at your direction; with the minimal-knowledge push relay we operate, limited to waking your device on new mail; with service providers strictly necessary to run the app (e.g. crash reporting, if you opted in), under contract; and when required by law or to protect rights and safety.
7. Data retention & deletion
- Your mailbox content lives in the encrypted database on your device. Uninstalling Mostpost, or removing an account in the app, deletes that local data (subject to OS backup behavior you control).
- Tokens / subscription metadata held by the push relay are removed when you unpair / disable push or remove the account.
- You can disconnect Google access at any time at Google Account → Security → Third-party access.
8. Security
Mostpost uses encryption at rest (encrypted local database), modern TLS in transit, post-quantum hybrid encryption for its end-to-end-encrypted features, and platform keychains for secrets. No system is perfectly secure, but we design to keep your data on your device and minimize what any server can see.
9. Children
Mostpost is not directed to children under 13 (or the equivalent age in your jurisdiction) and we do not knowingly collect their data.
10. Your rights
Depending on your location (including under the GDPR and CCPA), you may have rights to access, correct, delete, or port your data, and to object to certain processing. Because most data is stored locally on your device and under your control, you can exercise many of these directly in the app. For anything else, contact support@mostpost.io.
11. Changes
We may update this policy; we will post the new version here and update the effective date. Material changes will be surfaced in the app.
12. Contact
support@mostpost.io — Alvorado Digital.