# Mailcycle

> Programmable, privacy-first email for individuals, AI agents, automation and large-scale device fleets. An account is a twelve-word recovery phrase, incoming mail is sealed to a key only the account's devices and agents hold, and one account manages every address, device and agent it owns.

Mailcycle is inbound email infrastructure with an API, and an MCP server for AI agents. It is not a bulk sending, marketing or outreach tool. Free receives mail only. From Personal up, paired devices can write, reply and forward from their own addresses in the app, with files attached, within a daily limit set by the plan; sending over the API starts at Scale.

How it works, in short:
- An account has no email address, name or password. Creating one generates twelve words on the device; the server stores an opaque id, a public key, a plan and dates. There is no password reset, and losing the phrase loses the mail.
- Addresses are created on shared domains Mailcycle adds, or on domains a customer brings on Scale and above. mailcycle.email issues no customer addresses. Every shared domain is vetted before it is added (Spamhaus reputation, Wayback Machine history, a search of the name), and the server refuses one without those checks confirmed. Shared domains are grouped by plan, and an account reaches its own plan's group and those below it.
- A Worker is a device or browser paired to the account by scanning a QR code or typing an eight-digit code. It receives the addresses assigned to it and the keys for those alone, holds a device credential rather than an account, and can be removed on its own. While open it holds a live connection, so removal and address assignments reach it at once. It has inbox, sent, junk, trash and starred views; drafts stay on the device.
- An AI agent is a Worker with no screen, run by the `mailcycle-mcp` MCP server on the agent's own machine (Scale and above). It is paired by pasting a line from `npx -y mailcycle-mcp pair` into the app, which carries the key its address keys are sealed with. Its tools wait for, read and reply to mail, open attachments and send files, decrypted locally. Agents start reply-only, can be allowed to send to anyone at up to 20 an hour (60 on Fleet, 100 on Enterprise), and send only from the addresses assigned to them. The model provider the agent uses sees what it reads.
- Incoming mail is sealed to the address's public key before anything is stored, attachments included. Trackers are stripped on the device when a message is opened. Sent mail passes through in plain text and is not logged; the copy kept in the address's Sent folder, files included, is sealed to its key. Mail sent can carry up to 10 files, 3.5 MB between them, and program and script files are refused. Incoming messages over 25 MB are refused. Each paid plan has a daily sending limit: Personal 20, Operator 50, Scale 250, Fleet 1,000.
- Plans are metered on email addresses held, not devices: devices are unlimited on every paid plan. Free is $0 (3 addresses, 1 device, 3,000 messages received a month, receive only), Personal $7 (25 addresses, 50,000 received, 20 sent a day), Operator $15 (250, 250,000, 50, plus the API and webhooks), Scale $19 (1,000, 750,000, 250, plus sending from the API, AI agents and 10 of your own domains), Fleet $99 (10,000, 4,000,000, 1,000, 50 domains), Enterprise by arrangement.
- Payment is by card through Polar, or in cryptocurrency through NOWPayments. On the web either can top up an account balance, from $15 to $2,000, which the plan takes its monthly price from before any card is charged.
- Support requests can be written in the app. They are encrypted on the device to the account's key and the support team's, so the server stores ciphertext it cannot read. support@mailcycle.email works too.
- Retention defaults to 7 days and caps at 90. Deleting an account erases its addresses, devices and mail immediately; payment records, the audit log and hashes of retired addresses are kept, as the Privacy Policy lists.

The iOS and Android apps are on the App Store (https://apps.apple.com/app/id6816296566) and Google Play (https://play.google.com/store/apps/details?id=email.mailcycle.app). Webhooks and an account event stream are built; API access to both is on Operator and above. The SDKs are published as mailcycle-sdk on npm (TypeScript), mailcycle on PyPI (Python), mailcycle.email/go (Go), mailcycle on crates.io (Rust), mailcycle.email/swift/mailcycle.git (Swift), mailcycle/mailcycle from the Composer repository at mailcycle.email/php (PHP), email.mailcycle:mailcycle on Maven Central (Java), Mailcycle on NuGet (.NET) and mailcycle on RubyGems (Ruby).

## Docs

- [AI agents](https://mailcycle.email/agents/): an email address for an AI agent, through MCP, and what sees what.
- [Download](https://mailcycle.email/download/): the iOS app (iOS 16.4 or later), the Android app (Android 7.0 or later), the web app, the Worker APK for phones with no Google Play, and the MCP server for AI agents.
- [Product overview](https://mailcycle.email/product/): the Operator console, Worker devices, AI agents, pairing, and what each screen does.
- [Email API](https://mailcycle.email/developers/): what the HTTP API does, how mail comes back sealed, webhooks and the event stream, the API conventions, and the limits on sending.
- [Developer docs](https://docs.mailcycle.email/): the HTTP API at https://api.mailcycle.email, with a quickstart, authentication and API keys, guides, every endpoint, error codes and rate limits.
- [Email SDKs](https://mailcycle.email/sdks/): every SDK, its package and its install line. Each derives keys from the recovery phrase on your machine to create addresses that receive mail, open what arrives, send replies and verify webhooks.
  - [Python](https://mailcycle.email/sdks/python/): `pip install mailcycle`, Python 3.10 or later.
  - [TypeScript and Node.js](https://mailcycle.email/sdks/typescript/): `npm install mailcycle-sdk`, Node 20, Deno, Bun, Cloudflare Workers and browsers.
  - [Go](https://mailcycle.email/sdks/go/): `go get mailcycle.email/go`, Go 1.26 or later.
  - [Rust](https://mailcycle.email/sdks/rust/): `cargo add mailcycle`, Rust 1.75 or later.
  - [Java](https://mailcycle.email/sdks/java/): `email.mailcycle:mailcycle` on Maven Central, Java 17 or later, usable from Kotlin.
  - [C# and .NET](https://mailcycle.email/sdks/dotnet/): `dotnet add package Mailcycle`, .NET 8 or later.
  - [PHP](https://mailcycle.email/sdks/php/): `mailcycle/mailcycle` from the Composer repository at mailcycle.email/php, PHP 8.1 or later.
  - [Ruby](https://mailcycle.email/sdks/ruby/): `gem install mailcycle`, Ruby 3.1 or later.
  - [Swift](https://mailcycle.email/sdks/swift/): Swift Package Manager from https://mailcycle.email/swift/mailcycle.git, Swift 5.9 on macOS 13, iOS 16 or Linux.
- [SDK guides](https://docs.mailcycle.email/guides/sdks/): the full reference for each SDK in the developer docs.
- [Email MCP server](https://mailcycle.email/mcp/): `mailcycle-mcp`, its seven tools and their inputs, setup for Claude Code, Claude Desktop, Cursor, Codex and VS Code, and the send modes.
- [Security](https://mailcycle.email/security/): the threat model, what is encrypted and what is not, what Mailcycle can still see, and how to report a vulnerability.
- [Pricing](https://mailcycle.email/pricing/): every plan, its limits, and what a payment identifies about you.
- [Solutions](https://mailcycle.email/solutions/): individuals, AI agents, developers, automation, teams and device fleets.

## For agents

Every page on mailcycle.email is also served as Markdown: request it with `Accept: text/markdown`, or append `index.md` to the page's URL, as in https://mailcycle.email/pricing/index.md.

- [auth.md](https://mailcycle.email/auth.md): how an agent or script gets credentials for the API: MCP pairing, API keys, or a session from the recovery phrase.
- [Agent skills](https://mailcycle.email/.well-known/agent-skills/index.json): instructions an agent can load, for giving itself an email address through `mailcycle-mcp` and for using the API and the SDKs in nine languages.
- [API catalog](https://mailcycle.email/.well-known/api-catalog): the API's base URL, its docs and its health check, as an RFC 9727 linkset.

## Legal

- [Terms of Service](https://mailcycle.email/legal/terms/)
- [Privacy Policy](https://mailcycle.email/legal/privacy/): every category of data stored, and how long each is kept.
- [Acceptable Use Policy](https://mailcycle.email/legal/acceptable-use/)
- [Data Processing Agreement](https://mailcycle.email/legal/dpa/)
- [Refund Policy](https://mailcycle.email/legal/refunds/)
- [Cookie Policy](https://mailcycle.email/legal/cookies/): the site sets no cookies; the app stores keys on the device.
- [Accessibility](https://mailcycle.email/legal/accessibility/): what is tested, what is not, and what is known not to work well.
- [Notices](https://mailcycle.email/notices/): dated notices of changes to the terms and policies, subprocessor changes and service notices, with an Atom feed at https://mailcycle.email/notices/feed.xml.
- [Delete your account](https://mailcycle.email/delete-account/): how to delete an account in the app, what is deleted and kept, and what happens if the recovery phrase is lost.

## Optional

- [About](https://mailcycle.email/about/): why Mailcycle exists, and what it costs to work this way.
- [Contact](https://mailcycle.email/contact/): support@mailcycle.email for account help, abuse@mailcycle.email to report an address, hello@mailcycle.email for sales, security and legal.
- [Web app](https://app.mailcycle.email): where an account is created and managed.

Operated by Northlab Studios Ltd, registered in England and Wales.