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

npx -y @openagentemail/setup

A guided wizard: it checks what you already have, helps you pick a VPS and a

domain if you're missing either, and connects your agent clients (Claude Code,

Cursor, Kimi Code…) once the server is up.

The manual path needs 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, mailbox password, and NTFY_ADMIN_PASSWORD
docker compose up -d
sudo ./deploy/dns-records.sh   # prints the exact DNS records to create

Then verify everything end to end:

sudo ./deploy/doctor.sh

`doctor.sh` checks `.env` permissions; MX, A, SPF, DKIM, and DMARC; PTR;

outbound port 25; DNS blocklists; TLS certificates on 465 and 993; and the

server-side ntfy verification endpoint. It does not log in over IMAP/SMTP or

send a round-trip test. Docker Mailserver can create `docker-data/` as root,

so use `sudo` for these two scripts; an EACCES failure prints the same retry

instruction instead of pretending the DKIM key is missing.

If no SMTP relay is configured and outbound port 25 is blocked, API

`queued:true` only means the local mailserver accepted the message. It does

not mean the recipient received it: Postfix can retain the message in its

queue. Treat doctor's outbound-port-25 result as the delivery prerequisite, or

configure a relay before relying on direct delivery.

Public TLS with Let's Encrypt (opt-in)

The default `docker compose up -d` path remains self-signed: it does not start

or pull Certbot and does not publish TCP 80. To use a publicly trusted mail

certificate, opt in only after `mail.$DOMAIN` has an A (and, if used, AAAA)

record pointing at this host and the firewall permits inbound TCP 80. HTTP-01

cannot create those DNS or firewall prerequisites for you.

In `.env`, set the following (use a reachable contact address outside this

mailserver when possible):

SSL_TYPE=letsencrypt
SSL_DOMAIN=mail.example.com       # exactly mail.$DOMAIN
LETSENCRYPT_EMAIL=admin@example.net  # optional, but recommended

First issue the certificate with the explicitly enabled sidecar; do not start

the mailserver in `letsencrypt` mode before this succeeds:

docker compose --profile letsencrypt-bootstrap up -d certbot-bootstrap
docker compose logs -f certbot-bootstrap
# Wait for “Successfully received certificate”, then confirm:
docker compose --profile letsencrypt-bootstrap run --rm --no-deps \
  --entrypoint ls certbot-bootstrap -l \
  /etc/letsencrypt/live/mail.example.com/fullchain.pem \
  /etc/letsencrypt/live/mail.example.com/privkey.pem

This temporary container reads the shared certificate volume, so confirmation

still works after the one-shot bootstrap has stopped.

If first issuance fails, Certbot stops instead of retrying the ACME request in

a tight loop. Correct the DNS/port-80/domain prerequisite, then explicitly run

the same `docker compose --profile letsencrypt-bootstrap up -d certbot-bootstrap`

command again.

The entire `/etc/letsencrypt` tree is a persistent named volume shared with

the mailserver read-only: Certbot's `live/` files are symlinks into `archive/`,

so mounting only `live/` is incorrect. Once the first certificate exists,

start the full opt-in stack and verify the public endpoints. Do not enable

`letsencrypt-bootstrap` and `letsencrypt` together: both publish host TCP 80.

docker compose --profile letsencrypt up -d
./deploy/doctor.sh
openssl s_client -connect mail.example.com:465 -servername mail.example.com /dev/null | openssl x509 -noout -issuer -subject -dates
openssl s_client -connect mail.example.com:993 -servername mail.example.com /dev/null | openssl x509 -noout -issuer -subject -dates

After bootstrap, the renewal sidecar runs `renew` every 12 hours and restarts

with Docker. docker-mailserver's change-detection service watches

`SSL_TYPE=letsencrypt` certificate updates and reloads Postfix and Dovecot, so

renewed certificates take effect on 465/993 without a manual container restart.

Keep the `letsencrypt` profile enabled for normal operation. If it is omitted,

the sidecars and TCP 80 are absent and the original self-signed path is unchanged.

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","scopes":["read:messages"]}'
# → 201 {"address":"fox-k7d2@example.com","name":"signup-bot","token":"oa_…","scopes":["read:messages"]}

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.

Paths are exact: call `/v1/notify`, not `/v1/notify/` — a trailing slash

returns a plain 404 rather than the API error format.

Using your own mail server

Already have a mail provider for your domain? Run the API by itself with

`compose.api-only.yaml`, connected to that provider's

catch-all mailbox. The external mail server guide

covers the required catch-all setup, Portainer deployment, SMTP sender limits,

and TLS certificate verification.

The standalone default project name is `openagentemail`. If the full

`compose.yaml` stack also runs on the same host, the API-only stack must not

share that default project: give it an explicitly different `-p` value or

`COMPOSE_PROJECT_NAME` so the two stacks cannot adopt each other's resources.

To run multiple API-only instances on one host, give every instance its own

environment file, unique Compose project, and host `API_PORT`. The API always

listens on port 3100 inside its container; `API_PORT` changes only the host-side

mapping. For example:

mkdir -p ../oae-api-only-env
cp .env.api-only.example ../oae-api-only-env/alpha.env
cp .env.api-only.example ../oae-api-only-env/beta.env
chmod 600 ../oae-api-only-env/*.env
# Set API_PORT=3100 in alpha.env and API_PORT=3101 in beta.env.
# Generate separate API_KEYS and TASK_SIGNING_SECRET values in each file.

docker compose -p oae-alpha --env-file ../oae-api-only-env/alpha.env -f compose.api-only.yaml up -d
docker compose -p oae-beta  --env-file ../oae-api-only-env/beta.env  -f compose.api-only.yaml up -d

You may set a unique `COMPOSE_PROJECT_NAME` for each command instead of using

`-p`. The project names make Compose generate distinct container names and

project-scoped named volumes (for example `oae-alpha_api-data` and

`oae-beta_api-data`). Do not reuse a project name or `API_PORT` between the two

instances. Each instance must have independently generated `API_KEYS` and

`TASK_SIGNING_SECRET` values; configure its IMAP and SMTP credentials for that

instance's intended mailbox/provider boundary as well. Keep these populated

environment files outside the repository, as in the example above.

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 Inbox / All Mail (IMAP) and Sent (API/MCP send audit

for 30 days; direct SMTP is not listed) with cursor paging, extracts

verification codes and links at the top of a message, offers Rendered

(isolated HTML iframe), Plain text, or Source views, and can mark messages

read or unread. Source is fetched on demand from a size-capped `no-store`

endpoint and never injected as HTML. Scheduled and Trash are omitted until

the backend can serve them.

Admin sessions can also create identities (with custom address prefixes),

rotate tokens, and delete identities directly from the overview table.

The browser exchanges the token once for an `HttpOnly` session cookie; manually

pasted tokens never enter the URL or browser storage. You can also bookmark

`https://myinstance:3100/ui?token=` for direct login; the token is

immediately stripped from the address bar via `history.replaceState` on load,

though tokens passed in URLs can linger in browser history and server access logs.

Percent-encode the token if it contains URL-reserved characters like `+`, `&`, or `#`

(e.g. `a+b` → `a%2Bb`), as `+` decodes to a space and `&` truncates the value.

Only open `?token=` links you generated yourself; if you suspect a link has leaked,

rotate the token from the UI immediately. Do not open `?token=` links sent by

others — the link signs you into the sender's session (the app displays a

visible "Signed in via link" banner across the interface for the session as the tell).

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. Each row also shows whether the identity has a token (green dot) and

has Rotate and Delete action buttons. A Create Identity button

above the table opens a form where you can set a custom address prefix (e.g.

`qa-bot`) or leave it blank for a random one; the new token is shown once in a

copy-to-clipboard modal. Identity sessions never see the overview or management

controls — 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 operations over a plain HTTP API and a first-class

MCP server your agents can call directly.

• Server-side notifications — private ntfy transport for human alerts and

managed-agent wake-ups, with OTP-only mail notifications by default. Topics

and ntfy credentials stay on the server; phone setup is deliberately a later

v0.3.1 step. Per-identity push content tiers control how much of each

mail-arrival alert leaves the server: tier 1 interrupt only (default),

tier 2 adds subject/from, tier 3 (admin + explicit risk confirm) adds a

short body preview and extracted OTP codes/links.

• `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". An identity may flag mail it received

or that this server actually sent (TO ∨ trusted Sent: From match and

Message-ID in the outbound registry), matching the Sent folder (#26 PR 2);

a forged From does not count. It cannot flag another identity's mail. Reading

a message never changes the flag by itself.

• Web dashboard for humans — inspect identities and messages at `/ui` (Inbox

is the default landing for every session). Inbox is a three-pane mail client

(identity/folder, list, detail) with Rendered / Plain text / Source; HTML

stays in a sandboxed iframe. Real `/ui/*` History routes cover Overview,

Tasks, Notifications, and Configure; the shell stays a zero-bundler

`/ui/styles.css` + `/ui/app.js` pair.

• 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,

docker-mailserver,

and a private ntfy container. 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.

Multi-domain support

You can configure secondary domains alongside the primary `DOMAIN` by setting `EXTRA_DOMAINS=domain2.com,domain3.org` in `.env`.

• Identities: Agents can be created on the primary domain or any configured secondary domain via the API (`POST /v1/identities` with `domain`), MCP tools (`mail_new_identity`), or the Web Dashboard modal. Note that creating the same localpart across different domains is not allowed for now and will be revisited in Part 2.
• Inbound & Outbound: Catch-all inbound matching and internal mail stamping (`X-OA-Mail-Stamp`) recognize all configured domains.
• Tasks & Alerts: Cross-domain tasks and notifications seamlessly support agents across all configured domains, with identical localparts across domains currently not allowed (409) pending a design revision, and agent-card endpoints still publishing the primary domain.
• Pending Deploy Automation: Automated deploy scripts (`deploy/dns-records.sh`, `deploy/doctor.sh`, Certbot SANs, and multi-domain DKIM key generation) currently configure the primary `DOMAIN`. Automated multi-domain provisioning scripts will follow in Part 2.

Optional compliance archive

Set `ALWAYS_BCC=archive@example.net` only when your compliance policy permits

an additional external delivery copy. It is off by default and adds the archive

once to the SMTP envelope for API, MCP, and task sends, preserving visible

recipient order and matching an existing recipient only by exact local-part and

case-insensitive domain—without adding a MIME `Bcc` header or

changing visible `To`, header From, envelope MAIL FROM, SPF, DKIM content, or

DMARC alignment. Archive mailbox access, privacy, retention, aliases, and

forwarding are operator/MTA responsibilities.

The archive is an independent, off-domain compliance destination—not an

ordinary untrusted recipient. For all-local visible recipients it receives the

exact MIME, including the `X-OA-Mail-Stamp` that preserves local `internal`

classification. Same-domain `ALWAYS_BCC` values are rejected at startup: on a

shared catch-all deployment they are not an independent archive destination,

and duplicate suppression is not a substitute for that boundary. Configure a

controlled external compliance mailbox or leave `ALWAYS_BCC` unset.

Every enabled archive requires an explicit `TASK_SIGNING_SECRET` of at least

32 characters. The application enforces only presence and that length minimum;

it does not prove entropy, so operators must generate a high-entropy secret

(the Compose examples use `openssl rand -hex 32`). The historical SMTP-password

fallback remains only when the archive is absent or blank. Both Compose

deployments already require the dedicated secret.

If at least one original recipient is accepted and the configured archive RCPT

is rejected, the API preserves Nodemailer's partial-success semantics and logs

a content-free warning, even when another original recipient was rejected. If

the archive is accepted while no original recipient is reported accepted, the

API fails instead. After an upstream SMTP server accepts or queues the archive

RCPT, later delivery failures appear in SMTP/Postfix/relay logs or DSNs rather

than synchronously in the API response.

SMTP result matching deliberately keeps local-part spelling exact. A relay that

rewrites accepted RCPT local-part case can therefore cause a conservative

failure/retry; configure relays to preserve RCPT spelling. Case-distinct archive

and original local-parts are intentionally separate SMTP mailboxes and can

produce two copies with a case-folding provider, so use consistent spelling.

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

Typed approval actions are JSON-only and limited to 65,536 canonical UTF-8 bytes, root-inclusive depth 10, and a server-clock lifetime of 30 days. Exact limits pass; REST and MCP surface `approval_action_too_large`, `approval_action_too_deep`, or `approval_expiry_too_far` as stable client errors when a bound is exceeded.

The exact v1 action-digest recipe and public cross-runtime vectors are in docs/approval-digest.md.

Task leases are opt-in; `TASK_LEASES_ENABLED` defaults to `false`, so existing clients remain compatible. If the flag is turned off after a lease exists, list/detail responses retain its safe timing and generation fields and add `leaseStatus: "disabled"`; no lease is silently cleaned up. A lease generation is capped at 24 hours from its initial claim, and no claim or renewal is allowed at or after seven days from the task's first claim; renewals cap their deadline rather than resetting either anchor, and equality is rejected. During an active recipient lease, omitting the optional credential retains `task_already_terminal`; a supplied wrong, malformed, expired, or reclaimed-generation credential returns `task_lease_required` at HTTP 409. The opaque `leaseToken` is only the claim bearer and is never listed, rendered, logged, or emailed.

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.

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

\* Push tiers 2/3 may relay subject/from or body/OTP via ntfy (off by default).

† AgentMail Outposts: email content stays in your AWS account; AgentMail still runs dashboard, auth, billing, and upgrades. BYOC ≠ open-source self-host on any VPS.

Roadmap

• v0.1 — REST + MCP, catch-all identities, `wait_for` with OTP/link

extraction, DNS wizard + doctor, optional SMTP relay.

• v0.2 — scoped per-identity tokens, send rate limits, automatic retention,

localhost-safe defaults, expanded OTP corpus.

• v0.3 (current) — built-in private ntfy notifications, OTP-aware IMAP

watcher, server-side agent wake-ups and notification ACLs. Phone delivery and

webhooks are intentionally out of this first release.

• 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/cloudflare-zero-trust.md — Cloudflare Tunnel and Access for the Dashboard without blocking MCP
• docs/agent-signup.md — let agents finish sign-ups that email a code, with a verified OKX wallet example
• 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