On your own Cloudflare account, on your own domain. The open-source
alternative to hosted agent-email APIs.
┌─────────────────────────── your Cloudflare account ───────────────────────────┐
│ │
│ any sender ──▶ Email Routing ──▶ one Durable Object per address │
│ │ parse · store · read-once state │
│ ├──▶ MCP server ◀── Claude / OpenClaw │
│ ├──▶ HTTP API ◀── your code │
│ ├──▶ webhook ──▶ n8n / Make │
│ └──▶ forward() ──▶ your real inbox │
│ │
└── nobody else's servers. nobody else's eyes. ──────────────────────────────────┘
Self-hosted email inbox for AI agents, on your own Cloudflare account
2026-11-14
ดาว
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เครื่องมือ
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อัปไทม์
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Why
Give an agent real work and it eventually needs to receive email.
Sign up for a service, there's a verification link.
Log in, there's an OTP. Register an account, reset a password, collect an invoice.
The loop always closes through an inbox.
Across the automation and agent systems I've worked on, the same wall comes up
every time. The agent is fully capable of the task, and then it stalls at
"check your email." The existing options are both bad in the same way. Either
you hand the agent the keys to your personal Gmail, or you rent an inbox from a
hosted API that reads everything passing through it.
So Mailslot is the third option. It's your agent's inbox, deployed to your
Cloudflare account in about ten minutes. Mail lands on your domain, gets parsed
and stored on your own infrastructure, and only your agents can read it.
The privacy here isn't a policy you have to trust. It's the architecture. The
mail never passes through anything of mine, because there is nothing of mine in
the path. No "we," just your account.
What your agent can do
Tool
What it does
list_messages
Browse and filter messages (sender, subject, body)
get_message
Fetch a full message (text, HTML)
extract_otp
Pull the verification code out of a message (read-once)
extract_links
Pull magic links / verification URLs
wait_for_message
Block until matching mail arrives (or timeout)
create_address
Mint a fresh address on demand, one per task, never reused
Exposed three ways, same engine:
MCP server: point Claude, OpenClaw, or any MCP client at it
HTTP API: token-auth REST for your own code
Webhooks: message.received pushed to n8n, Make, or anything with a URL
Quick start
npx create-mailslot
Ten minutes, interactively. It scaffolds a project you own, provisions
storage and an API token, deploys the worker, walks you through Email Routing
setup (a Cloudflare API token, or guided dashboard steps with live DNS
verification), and finishes with a live round-trip. Send an email from your
phone, watch it arrive in your terminal. Flags for non-interactive use are in
the wizard's README.
Requirements: Node 18+, a Cloudflare account (free tier works), and a domain
on Cloudflare.
⚠️ Domain reality check (the wizard enforces this): Email Routing is
zone-level. If a domain's apex already receives mail elsewhere (Google
Workspace, Lark, O365, and so on), that domain cannot host Mailslot at all,
not even on a subdomain, without breaking its existing mail. Use a separate
domain. (Subdomains work fine on zones where Email Routing is already
enabled.)
git clone https://github.com/mailslot/mailslot && cd mailslot && npm install
cd packages/core
# 1. Storage + auth (one-time)
npx wrangler r2 bucket create mailslot-raw
openssl rand -hex 24 | npx wrangler secret put MAILSLOT_TOKEN # keep a copy!
# 2. Deploy, baking in your mail domain (persists across future deploys)
npx wrangler deploy --var EMAIL_DOMAIN:mail.example.com
Enable Email Routing on your domain in the Cloudflare dashboard
(zone → Email Routing), respecting the domain reality check above.
Point mail at the worker: Email Routing → Routing rules →
Catch-all → action Send to a Worker → mailslot → Enabled.
Round-trip test:
TOKEN=<your token>
WORKER=https://mailslot.<your-subdomain>.workers.dev
# mint an address, send any email to it, then:
curl -s "$WORKER/v1/inboxes/<address>/wait?timeout_s=90" \
-H "Authorization: Bearer $TOKEN"
Config lives in two instance-specific values that survive every deploy
(keep_vars): EMAIL_DOMAIN (a var, editable in the dashboard) and
MAILSLOT_TOKEN (a secret). The repo's wrangler.jsonc stays generic.
Optional: FORWARD_TO plus FORWARD_MODE=all (copy mail to a verified
address), and WEBHOOK_URL / WEBHOOK_SECRET (signed message.received
events).
An agent signs itself up for a service, end to end:
agent: create_address() → [email protected]
agent: (signs up at the service using that address)
agent: wait_for_message(timeout=120)
agent: extract_otp() → "482913" [marked read-once]
agent: (submits the code, done)
No human inbox touched. No credentials shared. The address is disposable. Mint
a new one per task.
Why self-hosted
Hosted agent-email APIs
Mailslot
Who can read your mail
The provider
Nobody but you
Domain
Theirs (or delegated)
Yours
Mail storage
Their infrastructure
Your CF account (DO + R2)
Pricing model
Per-inbox tiers
Cloudflare's free tier goes far
Auditability
Trust the policy
Read the code
Works offline from vendor
No
There is no vendor
Hosted APIs are a fine product. This is for the people and companies for whom
"a third party processes all my agent's mail" is a non-starter: self-hosters,
automation agencies deploying for clients, and anyone whose compliance team
asks where the data lives.
Standard Cloudflare stack, thin on top. If you can maintain a Worker, you can
maintain this.
Integrations
MCP: works with any MCP client today (Claude Code, Claude Desktop, OpenClaw, custom agents)
n8n: community node (trigger + actions), in progress
OpenClaw skill: points at your instance, not a hosted cloud, in progress
Adapters are thin wrappers over one versioned event schema and one tool API.
Want an adapter that isn't here yet? The contract is small, so PRs are welcome.
onStored(email, message) extension hook: subclass Inbox for custom
per-deployment logic. Core stays a clean library with no business logic;
the live instance (@mailslot/instance) uses the hook for return-receipt
auto-replies (replyToEmail, no ESP). See instance/README.
n8n community node, OpenClaw skill
Deliberately not planned: hosted multi-tenant service, AI triage of your
personal mail, reading anything it doesn't have to. Boring, auditable plumbing.
Need it deployed for you?
I do fixed-price integrations. Your domain, your Cloudflare account, wired into your n8n or agent stack, with a handover doc.
Email [email protected] and tell me what you're building.
