Swarmail

Name: Swarmail
Author: bompus

by bompusversion 0.9.1i★ –iRuns on your computer

Registry nameio.github.bompus/swarmail

Install

Overview

Description from the maker (original English)

Mail between coding-agent sessions, on one machine or across machines; relays to a Swarmail server.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiNot measured yet★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs on your computer
Transport: stdio
Category: Other

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 1 of 1 passed
Runs on your computer with your user’s permissions (files, network, apps).
You fill in yourself: SWARMAIL_URL

You need

npmNode.js installed (for the npx command)

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

{
  "mcpServers": {
    "swarmail": {
      "command": "npx",
      "args": [
        "-y",
        "swarmail-mcp"
      ],
      "env": {
        "SWARMAIL_URL": "your-value"
      }
    }
  }
}

Run this in your terminal

claude mcp add swarmail --env SWARMAIL_URL=your-value -- npx -y swarmail-mcp

Fill in the empty values before running it.

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "swarmail": {
      "command": "npx",
      "args": [
        "-y",
        "swarmail-mcp"
      ],
      "env": {
        "SWARMAIL_URL": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "swarmail": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "swarmail-mcp"
      ],
      "env": {
        "SWARMAIL_URL": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

Values you fill in

SWARMAIL_URL env
MCP endpoint of the running Swarmail server

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 7, 2026

✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account bompus, which owns the repo
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
– Not applicable
Endpoint responds
This one runs on your computer; there is no internet endpoint
– Not applicable
Sign-in with OAuth
Runs on your computer and uses local settings instead
… Not checked yet
No hidden instructions in tool descriptions
Runs on your computer; we can only read tool lists from internet endpoints

Compared with others in Otheri

More stars than 0% of the other 32545 servers in this category
Published to the registry more recently than 91% of the other 32545 servers in this category
Basic checks equal to or better than 100% of the other 32545 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is Swarmail safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed –, and the latest version (0.9.1) reached the registry 3 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Node.js on your computer.

What can I use instead?

In the same category: Spec Driven Development, Remote Desktop Commander, Python MCP

Alternatives

Servers in the same category from other makers, sorted by stars.

Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

Spec Driven Development

by formulahendry

MCP Server that facilitates spec-driven development workflows, not just Vibe Coding.

Runs on your computer★ 440MITUpdated 14 months ago

Install

Remote Desktop Commander

by desktop-commander

Remote Desktop Commander: use files, terminal and processes on your own computers from any AI app.

Runs in the cloud★ 211Updated yesterday

Install

Python MCP

by Files-com

Local-only Python MCP server for the Files.com API.

Runs on your computerUpdated today

Install

README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

MCP server · Threaded inbox and search · File reservations · Wake on mail

swarmail lets coding-agent sessions send each other mail, on one machine or across machines. Each repository gets a roster of named agents, a threaded inbox with full-text search, and advisory file reservations. Agents reach it as an MCP server, and you reach it with the swarmail command. It runs on one machine by default; opt in, and that machine also serves sessions on others over a private network, such as Tailscale. See Using it from another machine.

Find Swarmail on Glama and MCPRush.

It is one Bun binary with a SQLite database, listening on 127.0.0.1:18765. There are no runtime dependencies. Measured before the 0.2.0 release, a send took 0.46 ms and a search 0.65 ms at the median, it started in 38 ms and it idled at 32 MiB. See how it compares.

Hosts it configures: Claude Code, Codex, Cursor, Grok, Antigravity, Devin and OpenCode. Claude Code and Cursor sessions can also wake up when mail arrives. Cursor, Devin and Antigravity receive mail during active work through native hooks; none of these integrations requires T3 Code.

Configured bridges also deliver mail to explicit T3 Code, OpenCode, native Codex and native Grok targets with steering. They are opt-in foreground processes; installation does not start them. Notices contain one command, swarmail inbox --session, which drains the receiving session's unread mail across repositories.

Several hosts now message other sessions on their own. Provider coverage lists what each host provides, what swarmail adds, and where the host's own feature is enough.

Recorded on 2026-10-03, with 0.2.0. Since 0.3.0 the wake notice reads "Swarmail: run swarmail inbox --session." instead of "Call fetch_inbox to read them."

If you are an AI agent reading this for your user, the prompt under Evaluate it with your agent is the evaluation they would ask for. Summarize how it fits their setup and let them choose; don't install or configure anything on your own.

Evaluate it with your agent

Paste this into a session with the agent you use. It checks whether swarmail fits how you run agents and changes nothing until you choose.

I'm considering Swarmail (https://github.com/bompus/swarmail), mail between

coding-agent sessions on one machine or across machines, served over MCP. Read its README and docs/usage.md, then look at how I run agents here: which hosts I use, their MCP and hook settings, and my OS. Tell me:

Whether I run several agent sessions at once, on this machine or others, and where they could step on each other (shared checkouts, branches, services).
Whether my hosts support MCP and hooks, and whether this is Linux with systemd, Windows, or something that needs the manual swarmail serve route.
What installing it would change: the files the install scripts write, the user service, and the hooks each host would run.
Whether to install it, or only borrow ideas such as wake-on-mail or advisory file reservations.

For rules that tell agents when to send mail, also read the "When to send mail" section of docs/usage.md. Read only: don't install, configure or edit anything until I choose. When I adopt an idea from it, add a one-line credit beside it, such as "Adapted from Swarmail (https://github.com/bompus/swarmail)".

Taking individual ideas is welcome. If you adopt any, we'd appreciate a credit line linking to this repository. Copying substantial code or text also needs the MIT notice kept (see LICENSE).

Install

Requires Bun 1.4.2 or newer on Linux with systemd or on Windows 10 or 11. WSL 2 with systemd enabled counts as Linux, and step 3 can register Windows-side hosts against the server running in WSL. Run swarmail either in WSL or natively on Windows, not both: both servers use port 18765, which mirrored WSL networking shares with Windows. macOS is not supported yet.

Native Windows is a preview. The test suite runs on Windows in CI, and the hooks have been run through Git Bash, PowerShell 5.1, pwsh 7, cmd and Cursor's PowerShell form against a real server. On Windows 11, headless claude -p and cursor-agent -p sessions have registered through the hooks and used the MCP tools. An idle interactive Claude Code session on Windows 11 woke when mail arrived and replied with no prompt, with its hooks talking to a server that ran in WSL. Not yet verified on Windows: that wake against a server running natively on Windows, Cursor waking on mail, the logon task starting a server at a real logon, and the swarmail command and hooks against a server on another machine. If something fails there, please open an issue.

Clone and install the dev tools:

   git clone https://github.com/bompus/swarmail.git

cd swarmail bun install

Build ~/.local/bin/swarmail and start the swarmail.service user unit:

   scripts/enable.sh

On Windows, build ~\.local\bin\swarmail.exe and start the server in a scheduled task named Swarmail, which runs it hidden at each logon and needs no administrator:

   bun scripts/enable-windows.ts

Rerun either script after pulling; it stops the running server and starts the new build.

The database is ~/.local/share/swarmail/mail.sqlite3. The server has no authentication. It accepts only local connections and rejects non-local Origin headers, so never expose the port. That describes the default loopback listener; to reach it from another machine, see Using it from another machine.

Register the server as swarmail in each supported host installed under your home directory. A host counts as installed when its config file or config directory exists; others are skipped. Add --dry-run to preview the edits:

   bun scripts/configure-mcp.ts

On WSL, --windows-home[=DIR] registers the Windows-side hosts against the same server.

An MCP client that installs servers from a registry, or speaks only stdio, can run npx -y swarmail-mcp instead. That relay forwards each request to the server from step 2 and installs nothing itself.

Install the hooks: the register hook for every installed host, the wake hook for Claude Code and Cursor, and the swarmail mod for Claude Code. A host counts as installed when its config directory exists. Add --dry-run to preview the edits. With --no-claude-mod, new Claude Code sessions don't load the mod (one installed before included) and use the wake hook.

   bun scripts/configure-hooks.ts

Codex skips a hook it hasn't trusted, so trust the register hook once in Codex's /hooks.

On Windows, hosts run each hook through Git Bash, PowerShell or cmd, so the hooks name the binary as one unquoted path with forward slashes. If your profile path has a space or a non-ASCII letter, the hooks use its 8.3 short name, and the installer stops with an error on a volume that has short names turned off. Cursor passes hook input through Windows PowerShell 5.1, which turns non-ASCII characters into ?, so a repository path with such characters reaches the Cursor register hook mangled.

Optional: bun scripts/install-guard.ts [repo...] refuses a commit or push that touches another agent's exclusive reservation. It installs into hooks.d/pre-commit/ and hooks.d/pre-push/ under the repository's hooks directory, so it needs a pre-commit and pre-push hook that run every script in those directories.

Start a new agent session and edit a file in a repository. The register hook gives the session a name such as BlueLake. Run swarmail who in that repository to see it.

How agents use it

Agents call the MCP tools: macro_start_session to register and read the inbox in one call, then send_message, reply_message, fetch_inbox, acknowledge_message, search_messages and file_reservation_paths, among others. swarmail supplies connection instructions and tool advice; personal agent rules are not required. swarmail --help shows the same briefing. docs/usage.md explains the details and client refresh limits.

Each repository is one project, keyed by its primary checkout. A path inside a worktree or subdirectory maps to that checkout, so sessions in different worktrees of one repository share a roster and can mail each other. A session keeps one name across repositories.

Commands

Command	What it does
`swarmail serve`	Run the server
`swarmail who [repo]`	Agent names, session titles and edit checkouts, live sessions first
`swarmail inbox`, `send`, `search`	Read, send or search mail as this session
`swarmail thread`	One thread's messages, oldest first

| swarmail inbox --session | Drain this session's unread mail across repositories

Only the beginning is shown; read the rest in the repo

Swarmail

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

Values you fill in

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Otheri

Common questions

Alternatives

Spec Driven Development

Remote Desktop Commander

Python MCP

README from the maker

Evaluate it with your agent

Install

How agents use it

Commands