Zerosmtp MCP Server

Everything you need for the Microsoft 365 SMTP AUTH shutdown. Find out what breaks in your tenant, check whether your hardware has a way out, and keep it sending - including a free relay for the devices that will never speak OAuth. It runs locally over stdio via the published package.

People who work with smtp server, transactional email and postfix and want it reachable from Claude, Cursor, VS Code, or another MCP client. The project is written in Python.

VERIFIED ACTIVE

LAST COMMIT 2026-09-18 · ★ 5 · #27 OF 90 MAINTAINED EMAIL · VERIFIED 2026-09-18

MIT · Python servers · how we verify → /methodology

01 · Install Zerosmtp

before you install - you'll need

The README does not document required environment variables for a basic install.

Claude Code

claude mcp add msgwing-zerosmtp -- npx -y zerosmtp-mcp

Claude Desktop / Cursor / VS Code - add to config

{
  "mcpServers": {
    "msgwing-zerosmtp": {
      "command": "npx",
      "args": [
        "-y",
        "zerosmtp-mcp"
      ]
    }
  }
}

Same JSON for Cursor. For VS Code, rename the top-level key from `mcpServers` to `servers`.

Using another client? Same JSON, different key

Claude Desktop · mcpServers

Cursor · mcpServers

VS Code · servers

Windsurf · mcpServers

Zed · context_servers

Cline · mcpServers

Roo Code · mcpServers

Continue · mcpServers

LibreChat · mcpServers

Gemini CLI · mcpServers

Codex CLI · mcp_servers

Full setup guides: every client.

02 · Evidence

Security posture

What to check before giving this server access to your agent - from the registry, GitHub, and our own probes. We don't score safety; we show what's verifiable.

runs as local process (stdio) - runs on your machine with your user's permissions

license MIT - declared in the repository

npm package zerosmtp-mcp - unscoped; check the name against the project README before installing

registry namespace io.github.msgwing is GitHub-verified and matches the repo owner

03 · What Zerosmtp can do

Prose above is summarized from the project's README and registry record - no invented capabilities.

Latest releases

v1.8.0 · 2026-08-29

Competitive review, measured rather than recalled: the nearest comparable · project is referenced in 73 files across other people's repositories and this · one in 0 - not from lack of use, but because a config holding…

v1.7.0 · 2026-08-29

The project's own tool became worth installing, and the one GitHub surface it · was absent from is ready to list it. · Added · A GitHub Action. action.yml at the repository root checks outbound SMTP · from a runner and…

v1.6.0 · 2026-08-17

The relay's status is now visible where readers actually are, and the · automation around the project stopped lying about its own results. · Added · Live relay status in the header of every page on docs.msgwing.com…

04 · Who maintains Zerosmtp

zerosmtp is maintained by msgwing. It's the only MCP server we track from this author; the repo dates to Mar 2026.

05 · Facts

repository: github.com/msgwing/zerosmtp
category: email - ranked #27 of 90 actively-maintained email servers as of 2026-09-18.
release cadence: 7 releases in the last 90 days (latest 2026-08-29)
registry: io.github.msgwing/zerosmtp (active, first published 2026-09-01)
packages: npm:zerosmtp-mcp

06 · Zerosmtp FAQ

What is Zerosmtp?

Is Zerosmtp still maintained?

Yes - as of 2026-09-18, its last commit was 2026-09-18 and it shipped 7 releases in the last 90 days. We re-verify nightly.

How do I install Zerosmtp?

Run `npx -y zerosmtp-mcp`. The README does not document required environment variables for a basic install. You can also paste the ready-made client config above.

Does Zerosmtp run locally?

Yes - it's a stdio server: it runs on your machine (via npx) with your user's permissions. Your data stays local unless the server itself calls external APIs.

07 · Alternatives to Zerosmtp

Alternatives to Zerosmtp

Maintained email servers if Zerosmtp isn't the fit.

More email MCP servers · Multimail Dev MCP Server · Maket · Imap MCP Server · Nitrosend

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