io.github.ni-c/smtp-mcp

@ni-c/smtp-mcp

MCP server that sends mail over SMTP, gated behind an allowlist and a human confirmation

304/wk GitHub npm

No known CVEs

MIT license

Actively maintained

Last commit 4d ago

Works with most clients

Transport: stdio, sse, http

0 tools

Grade F

MCPpedia last refreshed this data 22h ago

Edit this pageView history

io.github.ni-c/smtp-mcp is an MCP server that MCP server that sends mail over SMTP, gated behind an allowlist and a human confirmation. Its tool list has not been published yet over stdio, sse and http, requires no API key, and scores 62/100 on MCPpedia's security, maintenance and efficiency rubric.

Communication

Step 1

Install in your client

Config is the same across clients - only the file and path differ.

Supported in Claude Desktopstdio, sse, http · Node 18+

Paste into ~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "smtp": {
      "env": {
        "SMTP_FROM": "Your Name <person@example.net>",
        "SMTP_HOST": "smtp.example.net",
        "SMTP_USER": "person@example.net",
        "SMTP_PASSWORD": "app-specific-password",
        "SMTP_ALLOW_SEND": "true",
        "SMTP_ALLOWED_RECIPIENTS": "@example.net"
      },
      "args": [
        "-y",
        "@ni-c/smtp-mcp"
      ],
      "command": "npx"
    }
  }
}

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What io.github.ni-c/smtp-mcp does

MCP server that sends mail over SMTP, gated behind an allowlist and a human confirmation

Test This Server

This server supports HTTP transport. Be the first to test it - help the community know if it works.

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Why this score

Five weighted categories - click any category to see the underlying evidence.

Score breakdown

62/100across 5 weighted dimensions

How we score →

0255075100

−38

Security

Maintenance

Efficiency

Documentation

Compatibility

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Security

OSV.dev

No known CVEs.

Checked @ni-c/smtp-mcp against OSV.dev.

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Frequently Asked Questions

Is io.github.ni-c/smtp-mcp safe to use?: io.github.ni-c/smtp-mcp has no known CVEs as of the latest MCPpedia security scan. It requires authentication to connect, which limits unauthorized access. Licensed under MIT.
How do I install io.github.ni-c/smtp-mcp?: io.github.ni-c/smtp-mcp supports copy-paste install configs on its MCPpedia page for Claude Desktop, Cursor, and Claude Code. Scroll to the Quick Install section and select your client.
What AI clients work with io.github.ni-c/smtp-mcp?: io.github.ni-c/smtp-mcp is compatible with claude-desktop, cursor, claude-code. It uses stdio and sse and http transport.
Is io.github.ni-c/smtp-mcp actively maintained?: io.github.ni-c/smtp-mcp is actively maintained - last commit was 4 days ago.

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Discussion

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Has anyone used this with Cursor?How do you handle auth?Any alternatives?

{ "mcpServers": { "smtp": { "env": { "SMTP_FROM": "Your Name <person@example.net>", "SMTP_HOST": "smtp.example.net", "SMTP_USER": "person@example.net", "SMTP_PASSWORD": "app-specific-password", "SMTP_ALLOW_SEND": "true", "SMTP_ALLOWED_RECIPIENTS": "@example.net" }, "args": [ "-y", "@ni-c/smtp-mcp" ], "command": "npx" } } }

smtp-mcp

A Model Context Protocol (MCP) server for SMTP, the protocol every mail server speaks to accept a message for delivery.

Lets MCP clients like Claude Code, Claude Desktop or Codex send, reply to and forward mail from one configured address — with a human approving every message.

Seven tools is the ceiling, not the floor: SMTP_ALLOW_TOOLS=essential registers a curated five instead, and a model picks the right tool far more reliably from five than from seven — see choosing which tools load.

What makes it different

It sends mail. That is why it is a separate server. Its counterpart imap-mcp reads a mailbox and deliberately has no way to send anything — that absence is its entire security argument, because an agent that can reach private data and process attacker-controlled content is only exploitable once it also has a way out. This server is that way out, so it does not get to make the same claim. It earns its place by narrowing the channel instead, and by living in its own process with its own credentials.

It is off when you install it. SMTP_ALLOW_SEND defaults to false. Until it is set the sending tools are not registered at all — absent from tools/list, not refused at call time.

It can only write to people you named. SMTP_ALLOWED_RECIPIENTS is required to turn sending on. Every address in To, Cc and Bcc is checked against it before a connection is opened

Frequently Asked Questions

Is io.github.ni-c/smtp-mcp safe to use?

io.github.ni-c/smtp-mcp has no known CVEs as of the latest MCPpedia security scan. It requires authentication to connect, which limits unauthorized access. Licensed under MIT.

How do I install io.github.ni-c/smtp-mcp?

io.github.ni-c/smtp-mcp supports copy-paste install configs on its MCPpedia page for Claude Desktop, Cursor, and Claude Code. Scroll to the Quick Install section and select your client.

What AI clients work with io.github.ni-c/smtp-mcp?

io.github.ni-c/smtp-mcp is compatible with claude-desktop, cursor, claude-code. It uses stdio and sse and http transport.

Is io.github.ni-c/smtp-mcp actively maintained?

io.github.ni-c/smtp-mcp is actively maintained - last commit was 4 days ago.

smtp-mcp

A Model Context Protocol (MCP) server for SMTP, the protocol every mail server speaks to accept a message for delivery.

Lets MCP clients like Claude Code, Claude Desktop or Codex send, reply to and forward mail from one configured address — with a human approving every message.

Listing the seven tools, then calling send_mail — which sends nothing and comes back asking, with the recipient and subject on their own labelled lines — and then a second call to an address outside the allowlist, which is refused before any connection is opened

What makes it different

It is off when you install it. SMTP_ALLOW_SEND defaults to false. Until it is set the sending tools are not registered at all — absent from tools/list, not refused at call time.

It can only write to people you named. SMTP_ALLOWED_RECIPIENTS is required to turn sending on. Every address in To, Cc and Bcc is checked against it before a connection is opened

... View full README on GitHub