openagent.email

Self-hosted email for AI agents. The open-source alternative to AgentMail.

openagent.email · website: openagentemail/website

One docker compose up on your own VPS gives every agent you run unlimited real mailboxes on your own domain — over REST and MCP — with OTP and verification-link extraction built in. No per-inbox pricing, no third party ever seeing your mail.

Quickstart

Prerequisites: a VPS with outbound/inbound port 25 open, and a domain you control.

git clone https://github.com/openagentemail/openagentemail.git && cd openagentemail
cp .env.example .env   # set DOMAIN, API_KEYS, and the mailbox password
docker compose up -d && ./deploy/dns-records.sh   # prints the exact DNS records to create

Then verify everything end to end:

./deploy/doctor.sh    # checks DNS, TLS, IMAP/SMTP login, and a round-trip send

Create an identity and hand your agent its scoped token (shown once):

curl -X POST http://localhost:3100/v1/identities \
  -H "Authorization: Bearer $API_KEY" -H "Content-Type: application/json" \
  -d '{"name":"signup-bot"}'
# → 201 {"address":"fox-k7d2@example.com","name":"signup-bot","token":"oa_…"}

The API binds to 127.0.0.1 by default — reach it from other hosts over an SSH tunnel or a TLS proxy: docs/security.md.

Read mail in a browser

Open http://localhost:3100/ui and paste an admin or identity API token. The built-in dashboard lists the addresses the token may access, shows messages, extracts verification codes and links, offers plain-text or isolated HTML previews, and can mark messages read or unread — its only write action.

The browser exchanges the token once for an HttpOnly session cookie; the token never enters the URL or browser storage. Sessions live only in API process memory, so restarting the API signs every browser out. They expire after 12 idle hours or 24 hours total — or tick Trust this device at login to keep a sliding 30-day session on that browser. Each token holds at most five sessions; a sixth login evicts that token's least-recently-used one instead of locking you out.

For another computer, use the same SSH tunnel recommended for the API or put a TLS reverse proxy in front. The login form refuses non-local plain HTTP, and session cookies are Secure away from localhost. Set UI_ENABLED=false in .env to make every /ui route return 404.

HTML email is treated as hostile input. The UI removes scripts, images, forms, links, sender CSS, and all attributes except numeric table spans, then loads the result in a separately sandboxed frame with a restrictive CSP. The sanitize-html 2.x dependency is deliberately pinned to an exact version; upgrade it in a dedicated change and rerun the full poison-message corpus.

Admin overview

An admin session lands on Overview: every identity in one table with the message count, unseen count, last delivery, and creation day, plus totals across the top. Identity sessions never see it — they go straight to their own inbox. The page is served from the same in-process API as the rest of /ui; there is no new public endpoint outside /ui/api.

What the numbers mean, and where they stop:

• Counts are a window, not a lifetime total. One scan reads the newest 500 messages in the catch-all mailbox and attributes each one to the identities it was delivered to. The header says newest N of M in the mailbox so the window is never mistaken for history. A message addressed to two identities counts once for each row and once — not twice — in the totals.
• Honest instead of round. Messages with enormous recipient lists can exceed the scanner's per-message and global memory bounds. Rows the scanner could not fully account for show ≥N or Unknown rather than a confident wrong number, the page explains why, and unmatchedInWindow is reported as null instead of a made-up zero. The same applies to an identity created after the last scan: it reads Unknown until the next one, never a false 0.
• Snapshots are cached in memory for 15 seconds and reused for up to 10 minutes while a refresh runs in the background, so opening Overview or walking in and out of inboxes does not hammer IMAP. Refresh is floored at 5 seconds. Restarting the API drops the cache — the first request afterwards pays for a fresh scan.
• Failures cool down and never lie. If a scan fails, the next attempt waits 5 seconds (the API sends Retry-After), the table keeps showing the previous numbers, and the header says the last refresh failed. Once a snapshot is older than 10 minutes it is not revived by a failed refresh: the page reports the counts as unavailable instead of showing stale data as current. While a cold scan is still running the endpoint answers 202 and the address list renders immediately with Loading… in the count columns.
• GET /ui/api/overview (browser session only, admin only) returns exactly the fields the page renders — never message content. ?refresh=1 asks for a new scan, subject to the 5-second floor and the failure cooldown.

Deliberate limits, so nothing here is a surprise later:

• Overview shows counts and timestamps only. Subjects, senders, and verification codes need per-message parsing, which is what the inbox view is for.
• New mail can be up to 15 seconds late on the page; Refresh fetches sooner. There is no steady-state polling: the page only schedules a follow-up while counts are loading or a refresh is pending, capped at 15 attempts over 20 seconds and paced by the server's own retry hint.
• A scan that misses its deadline is abandoned even if IMAP answers a moment later, and the next request scans again. The deadline covers connecting as well as fetching, so a hung server does not park a request behind IMAP's own 30-second socket timeout.
• Up to 200 identities render in one pass. Beyond that, expect to want paging or virtual scrolling; filtering and sorting happen in the browser today.
• The dashboard self-hosts the Satoshi webfont (/ui/fonts/*, the same typeface as the website) so it renders identically on every machine; font-src is 'self'. The favicon is an SVG (/ui/favicon.svg) so it needs no build step, and /ui/favicon.ico keeps returning 204 as before.
• Form controls use a dedicated --line-control border token so their outlines stay above 3:1 contrast. It is the one intentional deviation from the website's palette and is a one-line revert.

Features

• Unlimited identities — one catch-all mailbox, unlimited anything@yourdomain addresses. No provisioning, no per-inbox cost.
• Scoped tokens — every identity gets its own token that can only read and send as that address. The admin key never has to touch your agents.
• REST + MCP — the same seven operations over a plain HTTP API and a first-class MCP server your agents can call directly.
• mail_wait_for / POST /v1/messages/wait — long-poll an inbox until a matching message arrives, with OTP codes and verification links already extracted. Built for automated signups.
• Read/unread state — mail_mark_seen / POST /v1/messages/:id/seen lets an agent (or the human in the dashboard) mark a message handled, so the unseen count means "still needs attention". Reading a message never changes the flag by itself.
• Web dashboard for humans — inspect identities and messages at /ui, with an admin overview across all identities, responsive layouts, and doubly isolated HTML previews.
• Safety rails built in — per-identity send rate limits (20/hour default), automatic mail retention (30 days default), localhost-only API binding.
• Bring your own relay — send directly from the VPS, or route outbound through Amazon SES / SMTP2GO / any SMTP relay with one env var.
• DNS wizard + doctor — deploy/dns-records.sh generates your exact DNS records; deploy/doctor.sh diagnoses deliverability before your agents depend on it.
• Single dependency: Docker. The stack is the API plus docker-mailserver. Nothing else.

How it works

┌─────────────┐   MCP (stdio)    ┌──────────────────┐
│  AI agents   ├──────────────────▶                  │
│ (Claude Code,│                  │   openagent api  │
│  Cursor, …)  │   REST /v1/*     │  (Node, imapflow │
└─────────────┘──────────────────▶ │   + nodemailer)  │
                                   └────────┬─────────┘
                                            │ IMAP + SMTP (localhost)
                                   ┌────────▼─────────┐      SMTP 25
                                   │ docker-mailserver│ ◀──────────▶  the world
                                   │ catch-all mailbox│  (or your relay: SES, …)
                                   └──────────────────┘

One catch-all account on your domain receives everything. The API logs into it over IMAP, matches messages to identities by the To/Delivered-To header, and sends via SMTP with the From rewritten to the chosen identity. Polling + IMAP IDLE for low-latency waits.

Use it from your agent (MCP)

Requires Node.js 18+ on the machine running the MCP client — no install step, npx downloads and runs the package on first use.

claude mcp add openagentemail \
  --env OPENAGENTEMAIL_API_URL=http://localhost:3100 \
  --env OPENAGENTEMAIL_API_KEY=oa_your-identity-token \
  -- npx -y @openagentemail/mcp

Or the raw JSON config (Claude Desktop, Cursor, Kimi Code):

{
  "mcpServers": {
    "openagentemail": {
      "command": "npx",
      "args": ["-y", "@openagentemail/mcp"],
      "env": {
        "OPENAGENTEMAIL_API_URL": "http://localhost:3100",
        "OPENAGENTEMAIL_API_KEY": "oa_your-identity-token"
      }
    }
  }
}

Tools

Tool	Description
mail_new_identity(name?)	Create an identity; returns {address} (random localpart like fox-k7d2)
mail_list_identities()	List all identities
mail_list_messages(address, limit?)	List messages for an address (id/from/to/subject/date/seen/snippet)
mail_read_message(address, id)	Full message: text, html?, and otp:{codes:[],links:[]}
mail_mark_seen(address, id, seen?)	Mark a message read (default) or unread — reading never changes the flag by itself
mail_wait_for(address, fromContains?, subjectContains?, timeoutSec?)	Block until a matching message arrives (default 120s, max 600s)
mail_send(from, to, subject, text, html?)	Send mail; from must be an existing identity

Full per-client setup (Claude Code, Claude Desktop, Cursor, Kimi Code, generic): docs/mcp-clients.md · server details: packages/mcp/README.md

Why self-host?

• Privacy — OTP codes and verification links are credentials. Self-hosted, they never leave a machine you own. No third party reads, stores, or trains on your mail.
• Cost — a $5 VPS and a domain you already have vs. per-inbox/per-message SaaS pricing that scales linearly with your agent fleet.
• Control — your IPs, your reputation, your retention. No rate limits, no account suspensions, no sudden API deprecations.

Server requirements

Measured on our own production instance, idle: ~190 MB RAM total, ~0% CPU, and ~2 GB of disk for the Docker images. Mail itself is a rounding error — retention auto-deletes after 30 days.

Tier	Spec	Notes
Minimum	1 vCPU / 1 GB RAM / 10 GB disk	works with the defaults (ClamAV and SpamAssassin off)
Comfortable	1 vCPU / 2 GB RAM / 20 GB disk	headroom to enable SpamAssassin
With antivirus	4 GB RAM	ClamAV alone needs ~1 GB extra

That's a $5/mo VPS — or a $10–15/year deal box. The real prerequisite isn't size, it's port 25: AWS, GCP, Azure, DigitalOcean and Vultr block it by default (some unblock on request). Check before you buy — or route outbound through a relay and you don't need port 25 out at all.

Comparison

	openagent.email	AgentMail.to	MailSlurp
Open source	✅ Apache-2.0	❌	❌
Self-hosted	✅	❌	❌
Price	Flat VPS cost	Per-inbox subscription	Usage-based subscription
Unlimited inboxes	✅ (catch-all)	Paid tiers	Paid tiers
MCP-native	✅	✅	❌ (REST/SDKs)
OTP/link extraction	✅	✅	✅
Data leaves your infra	Never	Always	Always

Roadmap

• v0.1 — REST + MCP, catch-all identities, wait_for with OTP/link extraction, DNS wizard + doctor, optional SMTP relay.
• v0.2 (current) — scoped per-identity tokens, send rate limits, automatic retention, localhost-safe defaults, expanded OTP corpus.
• Next — outbound webhooks (push instead of wait_for polling), more write actions in the web dashboard, multi-domain support, Sieve-style per-identity rules.
• Distribution — planned one-click app in the OpenShip catalog.

Docs

• docs/api.md — REST API reference with curl examples
• docs/security.md — tokens, exposure, rate limits, retention
• docs/mcp-clients.md — MCP setup for every major client
• docs/dns-setup.md — DNS records, explained one by one
• docs/deliverability.md — the field guide to actually landing in the inbox

Contributing

Issues and PRs welcome — see CONTRIBUTING.md.

License

Apache-2.0