Envelope

📧 Envelope

U+1F4E7 — if you know, you know.

One inbox for all your email accounts, shared with your agents.

Why U1F4E7? It's the Unicode codepoint for 📧. Humans see a repo name. Agents see an envelope.

Setup • Travel • CLI • Rules • MCP • Agent plugins • vs. Alternatives • Dashboard • Commercial licensing • License

[Rust] [v1.3.26] [License: FSL-1.1-ALv2]

Envelope connects to the email accounts you already have (Gmail, Fastmail, iCloud, your own domain, any IMAP server) and puts them in one place. Open the Unified Inbox in your browser to read every account together, search them all at once, and archive or snooze across accounts in one pass. Your agents work the same mailboxes from the CLI, with JSON output, or over MCP, and anything they draft waits for your approval.

You don't change DNS, set up a new domain, or pay per-message fees. Add each address with its app password and go.

envelope accounts add --email [email protected]envelope accounts add --email [email protected]envelope serve                                     # every account in one inbox at http://localhost:3141envelope inbox --account [email protected] --json   # the same mail, for your agent

Install

# macOS or Linux: downloads the release binary for your OS and CPU, checks it# against the release's SHA-256 file, and installs it to ~/.local/bin (no sudo).curl -fsSL https://u1f4e7.com/install.sh | bash
# Homebrew (macOS or Linux) installs the same release binary.brew install tymrtn/u1f4e7/envelope# `tymrtn/u1f4e7/u1f4e7` is a live compat alias for the same formula.

To build it yourself instead:

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh && source "$HOME/.cargo/env"git clone https://github.com/tymrtn/U1F4E7cd U1F4E7cargo build --release# Add `--features governor` to build in the Governor send gate (see below).cp target/release/envelope ~/.local/bin/envelope

The release workflow signs and notarizes the macOS binaries once its Apple credentials are configured (docs/release-signing.md); until then macOS release binaries are unsigned. If macOS refuses to run an unsigned tarball you downloaded in a browser, clear the quarantine flag: xattr -d com.apple.quarantine ~/.local/bin/envelope.

Quick start

Envelope signs in to IMAP and SMTP with a password or an app password, and to Gmail with Google sign-in. That decides which mailboxes work today:

• Fastmail and iCloud Mail: create an app password in the provider's security settings.
• Gmail: envelope accounts add --provider google --email [email protected] signs in with Google in your browser; envelope accounts reauth [email protected] --provider google switches an account added with a password. While Envelope's Google app is in Google's testing stage, only addresses on its test-user list can sign in, and Google asks again every 7 days. An app password still works for accounts that can create one. From another device, add --paste (automatic over SSH), or run --paste --no-wait now and --finish - within 24 hours.
• Migadu, self-hosted Dovecot, and most other IMAP hosts: your normal mailbox password.
• Proton Mail: through Proton Mail Bridge, which needs a paid Proton plan. See Proton Mail for the setup.
• Outlook.com, Hotmail, Live, and Microsoft 365: not supported yet. Microsoft turned off password sign-in for IMAP on Outlook.com accounts and Exchange Online, so an app password does not help.

Envelope encrypts saved credentials with a passphrase. In a terminal it asks you for one. Scripts, agents, and the piped command below have no terminal to ask from, so give Envelope a passphrase file first:

# Create a random passphrase readable only by you, and point Envelope at it.# Add the export line to your shell profile, and back the file up: without it# the saved credentials cannot be decrypted.(umask 077 && openssl rand -base64 32 > "$HOME/.envelope-passphrase")export ENVELOPE_MASTER_PASSPHRASE_FILE="$HOME/.envelope-passphrase"
# Add an account. Envelope finds the IMAP/SMTP servers from the email domain# and logs in before saving; a rejected login fails here and prints what to fix.# (--skip-login-check saves without logging in, for offline setup.)printf '%s\n' "$APP_PASSWORD" | envelope accounts add --email [email protected] --password-stdin
# Verify setup end-to-end (paths → account → IMAP auth → inbox peek)envelope quickstart
# See folders with unread countsenvelope folders
# Read the inboxenvelope inbox --limit 20
# Read a message (does not mark it as read)envelope read 42
# Send with attachmentenvelope send --to [email protected] --subject "Report" --body "Attached." --attach report.pdf
# Reply in-thread as a reviewable draftenvelope draft reply 42 --body "Thanks."
# Snooze until Mondayenvelope snooze set 42 --until monday --reason waiting-reply
# Watch for new mail in real time (IMAP IDLE push)envelope watch --json
# Retrieve a verification-code JSON result for unattended automation (bounded and fail-closed)envelope --json code --account [email protected] --from [email protected] --wait 60
# Schedule a send for business hoursenvelope send --to [email protected] --subject "Report" --body "..." --at "monday 9am"
# Import contacts from your inbox, then create a contact-based ruleenvelope contacts import --from-inboxenvelope rule create --name "VIP" --match-contact-tag vip --action flag=\\Flagged
# Agent scores a message, creates a rule, Envelope enforces it foreverenvelope tag set 42 --score urgent=0.1 --tag newsletterenvelope rule create --name "Junk newsletters" --match-tag newsletter --match-score-below interesting=0.3 --action move=Junkenvelope rule run --confirm
# Unsubscribe from a mailing list (dry-run by default)envelope unsubscribe 99
# Open the local dashboard at http://localhost:3141 (loopback, no auth — single-user local trust)envelope serve
# Expose it to agents/devices on your tailnet — REQUIRES auth first.# Option A (humans): allowlist tailnet identities; `tailscale serve` proves them.envelope config set dashboard.tailscale_allow "[email protected],[email protected]"# Option B (agents/scripts): a bearer token (stored 0600, never echoed).envelope config set dashboard.auth_token "$(openssl rand -hex 32)"
tailscale serve --bg 3141
# See where Envelope is storing local stateenvelope paths

The dashboard opens as a three-pane mail shell. Unified Inbox is the default read-only surface and loads from the local message index; explicit refreshes or account/folder selections are what touch live IMAP mailboxes.

Actual sends are outbox-first. By default, an allowed send queues with a safety cooldown and the scheduled-send sweep performs the SMTP transmission later. Every agent send must declare factual attributes, and Envelope checks them against what it can observe before anything is queued or sent.

Governor scoring is a build-time Cargo feature, off by default. Homebrew and the release archives are built without it, so their sends are not scored by Governor, and send results and audit events record the gate as mode: "off". In those builds the draft-only ceiling still binds MCP sessions that carry an agent token, but an agent with shell access can send through envelope send (which defaults to autonomous-send), so give agents MCP with an agent token rather than a shell. Builds made with cargo build --release --bin envelope --features governor (or cargo install --path crates/cli --features governor) derive sanitized contextual attributes immediately before SMTP and ask Governor to score them with governor score --catalog envelope; only an opaque Governor allow sends. Those builds expect the Governor binary at the path pinned in SMTP_GOVERNOR_BIN (crates/email/src/outbound.rs), and every send fails closed when it is missing. Message bodies, full recipient addresses, attachment bytes, and secrets never enter the Governor request.

Dashboard URL metadata in --json output is discovered fresh for each UI construction or request, from an active local tailscale serve HTTPS route whose root proxy targets http://127.0.0.1:3141. It otherwise falls back to http://localhost:3141. Every agent-facing ui object reports that decision as dashboard_origin_source (tailscale_serve or localhost_fallback) and adds a non-secret dashboard_origin_warning only when discovery needs attention. MCP results omit these ui objects and skip Tailscale discovery unless the call passes include_ui_links: true, so the host's tailnet name stays out of model context by default. dashboard_path is always portable and remains the canonical handle for agents; dashboard.base_url and the legacy dashboard-base environment variables are retained only for compatibility and do not affect emitted agent UI links. Tailscale Serve keeps the dashboard tailnet-only; Tailscale Funnel publishes it on the public internet, so do not use Funnel for a mailbox dashboard unless that exposure is intentional.

Authentication (required before any non-loopback exposure)

On 127.0.0.1 the dashboard is an unauthenticated single-user local surface — the same trust boundary as your shell. The REST API reads and deletes mail, manages accounts, and queues sends, so the moment it is reachable by another device (a non-loopback --bind, or a tailscale serve front-end) it must require a credential. Configure one of:

• Tailscale identity allowlist (dashboard.tailscale_allow) — a request whose Tailscale-User-Login header (injected by tailscale serve) is in the allowlist is authorized. Humans just open the .ts.net URL; no token to type. Only safe behind tailscale serve, which sets and strips that header.
• Bearer token (dashboard.auth_token or ENVELOPE_DASHBOARD_TOKEN) — sent as Authorization: Bearer <token> (or X-Envelope-Token), compared in constant time. The path for Hermes/OpenClaw agents and scripts.

Once either is configured, every /api route returns 401 without a valid credential — including when tailscale serve fronts loopback. envelope serve --bind <non-loopback> refuses to start unless an auth method is configured. /api/health stays reachable for liveness probes but discloses local filesystem paths only to authorized callers. The CORS allowlist is a browser-only defense, not the access control.

Why not Himalaya / Cloudflare / Resend?

vs. Himalaya

Himalaya is a great CLI email client. Envelope is a CLI email client built for agents.

vs. Cloudflare Email Service

Cloudflare's Email Service (public beta, April 2026) is email infrastructure for the Cloudflare platform. Envelope is email mastery for your existing mailbox.

vs. Resend / Mailgun / SendGrid

Provider support

Envelope auto-discovers IMAP/SMTP from your email domain via DNS. Tested with:

Proton Mail

Proton Mail Bridge runs on your computer and serves your Proton mailbox over IMAP and SMTP on 127.0.0.1. Bridge is available only with a paid Proton Mail plan. Envelope's Bridge support has been tested against a stand-in server that presents a certificate shaped like Bridge's. Nobody has run it against Bridge itself yet, so please report what you find.

1. Install Bridge, sign in, and open your account's Mailbox details. Note the password Bridge shows there; Envelope signs in to Bridge with it, and your Proton account password won't work. Bridge uses IMAP port 1143 and SMTP port 1025 by default, with STARTTLS on both unless you change its connection mode.
2. Bridge encrypts those connections with a self-signed certificate it made when you set it up. Export it from Settings → Advanced settings → Export TLS certificates. Bridge writes cert.pem and key.pem to the folder you pick. Envelope needs only cert.pem; it skips any private key in the file and never stores one.
3. Add the account:

printf '%s\n' "$BRIDGE_PASSWORD" | envelope accounts add \  --email [email protected] --password-stdin \  --imap-host 127.0.0.1 --imap-port 1143 --imap-security starttls \  --smtp-host 127.0.0.1 --smtp-port 1025 \  --trust-cert ~/Downloads/cert.pem

--trust-cert makes this account accept exactly that certificate for its IMAP, SMTP and ManageSieve connections, in place of the public certificate authorities. Every other account checks certificates as before. If you set Bridge's IMAP connection mode to SSL, use --imap-security tls. Keep Bridge's SMTP on STARTTLS: Envelope uses SSL for SMTP only on port 465.

When Bridge's certificate changes, Envelope refuses the connection before it signs in and prints the fingerprints of the trusted and the presented certificates. Export the new certificate and trust it with envelope accounts tls --account [email protected] --trust-cert cert.pem. envelope accounts tls --account [email protected] shows what the account trusts now, and openssl x509 -noout -fingerprint -sha256 -in cert.pem prints a file's fingerprint in the same form.

MCP server

envelope mcp starts a Model Context Protocol server over stdio — drop-in email for Claude Code, Cursor, Zed, or any MCP runtime.

Framing follows the MCP stdio spec: one newline-delimited JSON-RPC message per line on stdout, nothing else on that stream (logs go to stderr). On stdin the server accepts newline-delimited JSON and, for callers written against versions before 1.1.0, the legacy Content-Length: framing — detected per message.

# Print a ready-to-paste config snippetenvelope mcp --config
# Output (paste into your MCP config):# {#   "mcpServers": {#     "envelope": {#       "command": "/path/to/envelope",#       "args": ["mcp"]#     }#   }# }

Tools include inbox, read, search, send, reply, create_reply_draft, create_forward_draft, modify_draft, get_draft, send_draft, move_message, flag, folders, tag, contacts, accounts, bulk, thread, rules_preview, rules_run, watch_status, snooze, plus threat_show and governor_catalog. Envelope is the only MCP email server that works against any IMAP provider.

For a single, distribution-ready operating guide to hand a fresh agent, see the Envelope agent skill.

For a walkthrough of running multiple agents from one shared inbox with scoped policies, see Agents at a glance.

The Dockerfile runs the MCP server in a container (docker build -t envelope ., then docker run -i --rm envelope). Mount a data directory at /home/envelope/data and pass ENVELOPE_AGENT_TOKEN for an agent created in it. Without a token, the container starts only when it has no database yet. It then creates a throwaway agent in that empty store, which has no mail accounts, so MCP directories can start the server and list its tools.

Use Envelope from your agent

Envelope ships as a plugin for Claude Code, Codex and Cursor, and as skills on skills.sh. Each install adds two skills: envelope for working mail, and envelope-setup for first-run setup. It also adds the local MCP server (envelope mcp).

Prerequisite: the envelope binary on PATH. The envelope-setup skill walks through this if it's missing.

curl -fsSL https://u1f4e7.com/install.sh | bash# orbrew install tymrtn/u1f4e7/envelope

tymrtn/u1f4e7/u1f4e7 is a live Homebrew compat alias for the same formula.

Then add your accounts and create a token for the agent. Run both in your own terminal, so your password and token never pass through the agent:

envelope accounts add --email [email protected]envelope agent create claude-code

Agent names are unique, and the free tier allows two active agents (envelope agent list shows them). Use one name per tool, or reuse one agent's token in several tools.

Claude Code (it asks for the token while installing):

/plugin marketplace add tymrtn/U1F4E7/plugin install envelope@envelope

Codex (it forwards ENVELOPE_AGENT_TOKEN from your shell environment):

codex plugin marketplace add tymrtn/U1F4E7codex plugin add envelope@envelope

Then, in an editor, add the token to the shell profile that starts Codex (for example ~/.zshrc). Typing it at the prompt would leave it in shell history.

export ENVELOPE_AGENT_TOKEN=<token>

Cursor Marketplace plugin: install Envelope from the marketplace, then set ENVELOPE_AGENT_TOKEN under Plugins → Configure. Listing copy is in MARKETPLACE.md.

Claude Desktop (MCP Bundle): download envelope-<version>.mcpb from the latest release and open it. Claude asks for the token, and for your passphrase file if you set ENVELOPE_MASTER_PASSPHRASE_FILE. The bundle carries its own envelope binary for macOS and Linux and uses the same accounts and data as the CLI.

Skills only (any agent that skills.sh supports):

npx skills add https://github.com/tymrtn/U1F4E7/tree/main/skills

Plugin versions follow Envelope releases; ci/check-agent-plugins.sh enforces it.

Rules engine

The agent is the intelligence. Envelope is the execution.

# 1. Agent reads inbox and scores each messageenvelope inbox --json | jq -r '.[].uid' | while read uid; do  envelope tag set "$uid" --score urgent=0.1 --score interesting=0.2 --tag newsletterdone
# 2. Agent creates rules from observed patternsenvelope rule create --name "Junk newsletters" \  --match-tag newsletter --match-score-below interesting=0.3 \  --action move=Junk
# 3. Preview, then explicitly confirm rule execution# Preview is read-only; --confirm is required for mailbox mutation.envelope rule previewenvelope rule run --confirm
# 4. Export to Sieve for server-side filteringenvelope rule export

The LLM teaches Envelope what to look for. Envelope applies those patterns deterministically. The LLM only re-engages when something new appears.

rShield

rShield scores every message for phishing and malware on your machine: clean, suspicious, dangerous, or unavailable when an analyzer that had to answer could not. Six local analyzers are on by default and send nothing anywhere.

envelope threat scan              # score the newest INBOX messagesenvelope threat explain 4812      # the signals and arithmetic behind a verdictenvelope threat report 4812       # draft a report to APWG (never sends)

Two optional analyzers are off until you enable them:

threat report also looks up abuse contacts over RDAP for the sending domain and, when there is one, the imitated domain, sending those domain names to their registries. Every outside lookup is logged as a lookup_performed event. Spamhaus restricts free and commercial use of its blocklists; read their usage terms first. Setup details, weights and the clamd walkthrough are in docs/rshield.md.

Dashboard

envelope serve starts a localhost web UI at http://localhost:3141.

• Left mailbox sidebar with Unified Inbox, Today/Needs Attention, Snoozed, Sent, Drafts, All Mail, and account mailboxes
• Middle message list with a permanent right-side reader
• Review page for agent drafts waiting on your approval, and a Logs page with each agent's history
• Reply / Reply-all with automatic header threading
• Compose with text/html toggle and file attachments
• ★ Snoozed virtual folder with overdue highlighting
• Search across every account with Gmail-style operators (from:, subject:, is:unread, before:)

Travel

Envelope Travel is a self-hosted itinerary and family-coordination workspace at /travel. It uses the Gmail or Google Workspace address you already own—no forwarding address or new travel account.

1. Turn on Google 2-Step Verification and create an app-specific password.
2. Run envelope serve, open Travel, and enter the address plus that app password. Envelope verifies Gmail before saving the encrypted credential. A fresh macOS install uses Keychain automatically; an existing encrypted file store remains in place. On a headless Linux host, set ENVELOPE_MASTER_KEY or ENVELOPE_MASTER_PASSPHRASE_FILE before starting the service.
3. Leave confirmations in the configured Gmail folder (INBOX by default), pick [Gmail]/All Mail in Travel settings to include archived confirmations, or paste a confirmation into the receipt desk. The mailbox scan is read-only: IMAP EXAMINE plus BODY.PEEK[] never marks mail as read.

The workspace groups flights, lodging, rail, cars, and activities into trips; keeps the source receipt and parser provenance; quarantines uncertain details for approval; detects emailed changes and cancellations; schedules reminders; and provides shared tasks. Family links are revocable and structurally omit confirmation codes, receipt text, private notes, and parser metadata. Each share also gets a separate read-only .ics capability, so Apple Calendar, Google Calendar, or another subscriber never receives task-edit authority.

For a computer-only install, keep envelope serve running while you need sync, alerts, family pages, or calendar refreshes; a sleeping laptop cannot poll Gmail. For access from family devices, the recommended remote shape is the Tailscale setup in Quick start. For an always-on Linux host, install the systemd user service from docs/install-linux.md, put ENVELOPE_HOME on persistent encrypted storage, require dashboard auth, and terminate TLS with Tailscale Serve or a trusted reverse proxy. Do not expose a mailbox dashboard anonymously. Gmail onboarding is deliberately disabled when Envelope binds directly to a non-loopback address: enter the app password only through localhost, or through an HTTPS/Tailscale proxy whose Envelope listener remains on loopback. A custom proxy must overwrite X-Forwarded-Proto with the actual client-facing scheme; plaintext proxy requests and conflicting HTTP browser origins are refused for Gmail credential setup.

Travel changes and delays currently come from messages received in Gmail. Live gate, aircraft, baggage-belt, and operational delay telemetry requires a separate flight-status provider and is not inferred when the airline has not emailed an update. Scheduled alerts appear in the Travel workspace; this build does not yet deliver push notifications when the browser is closed.

Commercial licensing

Personal use is free. Commercial rollout is a flat annual license sized by the number of mailbox users on one primary domain:

"Commercial use" means any use of Envelope by or for a company, team, agency, or paid project, including internal operations, customer workflows, or embedding Envelope in a product. "Mailbox users" means distinct human or service mailbox identities on the licensed domain that Envelope is configured to read, send, or automate. One person with multiple aliases on the same mailbox counts as one user. "Domain" means one primary email domain; subdomains of that primary domain are included, and additional unrelated domains require Enterprise.

Licenses are annual, non-transferable across organizations, and renew on the anniversary of issue. Request an annual license at [email protected].

Evidence bundles

envelope evidence collects a query-scoped, local evidence bundle while leaving the source mailbox read-only. Collection opens the requested folder with IMAP EXAMINE and fetches canonical raw RFC822 originals with BODY.PEEK[].

envelope evidence collect \  --account [email protected] \  --folder '[Gmail]/All Mail' \  --query 'FROM "[email protected]" SUBJECT "contract"' \  --include-thread \  --out ./evidence-bundle
envelope evidence verify --from ./evidence-bundleenvelope evidence verify --from ./evidence-bundle --strict

Structured filters can replace or combine with --query: --from-address, --to-address, --subject, --since, --before, --body, and repeatable --keyword. At least one filter is required unless the raw query is explicitly ALL.

Thread expansion is header-driven and bounded. By default, --include-thread fetches at most 500 messages while following Message-ID, In-Reply-To, and References links; adjust with --max-thread-messages. If the cap is reached, the bundle records a warning.

Evidence bundles intentionally expose message metadata, account identity, IMAP host/username, and local source paths for provenance. Treat bundles as sensitive even though they do not serialize passwords, OAuth tokens, or credential file paths.

Bundle layout:

evidence-bundle/  manifest.json  index.csv  README.md  SHA256SUMS  bundle.sha256  messages/<encoded-folder>/<uidvalidity>-<uid>.eml

Thread inclusion is driven only by Message-ID, In-Reply-To, and References; subject matching is never used as a fallback. Hash files provide local tamper evidence, not an external signature. Non-goals for the MVP: ZIP packaging, detached signatures, PST/mbox conversion, multi-account collection, mailbox mutation, and restore/import into a mailbox.

CLI reference

Every command supports --json for agent consumption.

Architecture

┌──────────────┐     ┌────────────────────────────┐     ┌──────────────┐│  AI Agent    │────▶│        Envelope (Rust)      │────▶│  Your SMTP   ││              │     │                              │     │  (Gmail,     ││  CLI / JSON  │     │  crates/cli       binary     │     │   Migadu,    ││              │◀────│  crates/email     IMAP/SMTP  │◀────│   Fastmail)  ││              │     │  crates/store     SQLite      │     │              ││              │     │  crates/dashboard web UI      │     │  IMAP/SMTP   │└──────────────┘     └────────────────────────────┘     └──────────────┘

Development

cargo build                # Build all cratescargo build --release      # Optimized release binarycargo test --all --features governor   # Also test with the Governor gate built incargo test                 # 194 tests, 0 failurescargo clippy               # Lint./ci/check-orphans.sh      # Verify every .rs file is reachable via mod

See CHANGELOG.md for per-release notes.

License

FSL-1.1-ALv2 — source-available, no competing services. Separate annual commercial licenses are available for organizational rollout, support, Enterprise/OEM terms, and uses outside the public license. The public license becomes Apache 2.0 two years after each release.

Copyright © 2026 Tyler Martin.

Built by Tyler Martin
Your agent shouldn't need a $50/month Resend plan to send an email.