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Mailcycle
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Private email for every device and every AI agent.

Programmable, privacy-first email built for individuals, AI agents, automation, and large-scale device fleets.

Get startedExplore Mailcycle

Nothing to sign up with · Free tier, no card · Unlimited devices on every paid plan

Mailcycle Home: mail in the last seven days, the latest mail, and the devices and AI agents on the account.
One product, the whole curve

The same Mailcycle at every size.

The account that holds your one private address is the account that provisions a thousand devices.

  1. 1address

    A private address of your own, created in seconds.

  2. 10devices

    A phone, a laptop, a few test handsets, all on one account.

  3. 100devices

    Tagged, searchable, managed in bulk from one console.

  4. 1,000+devices

    A fleet provisioned and controlled by one Operator.

Who it is for

Built for one address. Capable of ten thousand.

Six ways to use the same product.

Individuals

A private email address. Create one and read your mail.

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AI agents

An inbox your agent reads and answers through MCP. Mail is sealed the moment it arrives and opens on the agent's machine.

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Developers

Programmable email for applications and workflows. The console runs on the same API you get.

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Automation

Email addresses for automated systems, test environments and processes that need to receive real mail.

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Teams

Manage email identities across devices and workflows from one account, and share addresses with the people who work them.

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Device fleets

Provision and control email addresses across hundreds or thousands of connected devices. Devices need no accounts.

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One platform. Every inbox. Every device.

See all six in detail
AI agents

An inbox for your agent, sealed on arrival.

Give an AI agent its own email address. It waits for mail, reads it and replies through MCP, and decrypts on the machine it runs on. Mailcycle stores the same sealed mail it always does.

  • Its own addresses, not access to yours, and keys only for those
  • Waits for a code or a link and hands it straight to the agent
  • Replies only to whoever wrote, until you let it send to anyone
  • Mail passed to the model marked as the sender's words, not instructions
  • On Scale and above, removed in one tap like any device
How AI agents work
npx -y mailcycle-mcp pair

Run it where your agent runs and paste the line into the app. Then plug it into the agent you already use.

Claude Code setup
claude mcp add mailcycle -- npx -y mailcycle-mcp

Adds the server to Claude Code on this machine.

Read the setup guide
Operators and Workers

One place to manage every device and email address.

Mailcycle runs in one of two roles: the Operator who owns the account, or a Worker device attached to it.

Operator

The account, unlocked with the recovery phrase. An Operator manages devices, email addresses, assignments, plans, usage and account settings, and reads the mail for any address remotely, from a phone or a desktop.

How a device joins an account

  1. Worker device

    Opens Mailcycle, shows a code

  2. QR or pairing code

    Scanned or typed, single use

  3. Operator

    Confirms the device on the account

  4. Address assigned

    One address, or several

  5. Ready

    Mail arrives on the device

Pairing codes work once and can be cancelled, an unclaimed code is cleared after 14 days, and a device gets access only after you confirm it.

Capabilities

Everything a thousand devices needs, and nothing a single mailbox doesn't.

Instant addresses

Create an address in seconds and assign it or leave it unassigned. One action in the console, one call over the API.

Device pairing

Connect a device with a QR code or an 8-digit pairing code. The device needs no account or password.

Centralized management

Devices, email addresses, assignments, plans and usage all live in one Operator account, on any platform.

Several addresses per device

Assign one email address to a Worker, or several on Personal and above. Plans count addresses, not devices or seats.

Built for scale

Search, tag and filter the fleet, select many devices at once, and disable, enable or remove them in one action on Operator and above.

Cross-platform

The same app on iOS, Android and the web. The web app works today, on phones too; the store apps are coming soon.

Privacy-first by design

The four decisions everything else follows from.

The architectural choices behind Mailcycle's privacy.

Your account is twelve words

There is no sign-up form. Your device generates a twelve-word recovery phrase, and your account is made from it. The phrase and anything that opens the account never leave your device.

Mail is sealed before it is stored

Each email address has its own key, made on your device from your phrase. Every incoming message is sealed to that key before it is stored, and only your devices and the agents you connect can open it. Address labels and device names are encrypted on your device before we see them.

Trackers never fire

Remote content in mail is never fetched. Your device strips tracking pixels before it shows a message, and tells you what was removed and which host wanted it.

Deletion is the default state

Every email address has a retention window of 24 hours, 7 days, 30 or 90 days. Mail past it is deleted, and nothing is archived. Deleting your account erases its mail and devices immediately, with no grace period.

Some metadata is unavoidable, so we reduce it: device activity is rounded to five minutes, and email addresses get a generated name, like quiet.falcon, not yours. On Scale and above you can choose the whole name. Every shared domain is vetted before we add it, with its reputation, its history and its name all checked, so your addresses don't start out distrusted. The full architecture is written up here, including what we can still see and the design's limits.

Programmable

If it can be done in the console, it can be done over the API.

Mint email addresses, list and patch devices, assign and reclaim addresses, read mail, send from addresses you own. Every screen in Mailcycle is built on the same HTTP API.

Explore the APIWebhooksAvailable nowAn event streamAvailable now
POST /workers/:id/inboxes
# Give a device one of your email addresses
curl -X POST https://api.mailcycle.email/workers/wkr_8f21/inboxes \
  -H "Authorization: Bearer $MAILCYCLE_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{ "inboxId": "ibx_4c7a" }'

{ "ok": true }
Platforms

iOS, Android and the web.

One product, three platforms. Devices that cannot install an app run Mailcycle in the browser and pair the same way. The iOS and Android apps are not in the stores yet. The web app works on phones.

Open the web app
Questions

Frequently asked.

Plain answers on accounts, devices, agents and what we can and cannot see.

Yes. Create an account, create an email address, read your mail. Devices, pairing, tags and bulk operations are there when you want them.

Yes. The console is built on a public HTTP API, and anything it does can be done over that API, on any plan. From Operator, scripts can use API keys, and webhooks send your account's events to a URL you choose. See the email API and the docs.

On Personal and above, yes, from the addresses assigned to it, up to 20 messages an hour (more on Fleet and Enterprise) and within your plan's daily limit. A paired device can write, reply and forward in the app, and drafts stay on the device. Free receives mail only. Sending from the API starts at Scale. Sent mail leaves as plain text so the recipient's server can read it. The copy in Sent is sealed to the address's key.

Yes, on Scale and above. Run npx -y mailcycle-mcp pair where your agent runs, paste the line it prints into the app, and give the agent an address. It can then read, wait for and reply to mail through MCP. Mail is decrypted on the agent's machine, and every agent starts able only to reply to whoever wrote to it. See AI agents.

No. Worker devices have no accounts at all. Each one is paired to your account and can be removed on its own.

Devices are unlimited on every paid plan, and Free pairs one. Plans cap how many email addresses your account holds, assigned or not. A thousand devices sharing a hundred addresses costs the same as a hundred devices holding one each.

Its credential stops working immediately and its email addresses stay on your account, unassigned and ready for another device. It can be paired again.

No. Incoming mail is sealed to a key only your devices hold before it is stored, so we keep only ciphertext. We have no master key and no way to open it. Two limits: incoming mail is readable to our servers for the moment it takes to seal it, and mail you send leaves as plain text so the recipient's server can read it. See the security overview.

Your email addresses, since a mail server has to read the envelope to deliver. When a message arrived, how big it is, whether it has been read, which folder it is in and whether it is starred. For mail you sent, whether it went from the app, an API key, a device or an agent. Your retention setting, since our servers enforce the deletion. Each device's platform and when it was last active, to five minutes. Domains you bring. A log of account events, like a device paired or an address created, with the time. Your plan, when you signed up and, for paid plans, your payment records. Stored senders, subjects and bodies are ciphertext to us.

The account and its mail are gone for good. We have no email address to send a reset link to and no copy of your key. Write the twelve words on paper.

Start with one email address.

Create an account, mint an address and pair your first device in a few minutes. The same account scales to a fleet.

Get startedExplore Mailcycle