SMTP MCP Server

by ni-cio.github.ni-c/smtp-mcpv0.2.0

Send, reply to and forward mail over SMTP, restricted to a recipient allowlist, with each message approved by a person before sending.

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security

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freshness

Active3d ago

Install SMTP MCP server

claude mcp add smtp -e SMTP_HOST='<smtp-host>' -e SMTP_USER='<smtp-user>' -e SMTP_PASSWORD='<smtp-password>' -e SMTP_FROM='<smtp-from>' -- npx -y @ni-c/smtp-mcp

{
  "mcpServers": {
    "smtp": {
      "command": "npx",
      "args": [
        "-y",
        "@ni-c/smtp-mcp"
      ],
      "env": {
        "SMTP_HOST": "<smtp-host>",
        "SMTP_USER": "<smtp-user>",
        "SMTP_PASSWORD": "<smtp-password>",
        "SMTP_FROM": "<smtp-from>"
      }
    }
  }
}

Add to ~/.cursor/mcp.json (global) or .cursor/mcp.json (project).

{
  "mcpServers": {
    "smtp": {
      "command": "npx",
      "args": [
        "-y",
        "@ni-c/smtp-mcp"
      ],
      "env": {
        "SMTP_HOST": "<smtp-host>",
        "SMTP_USER": "<smtp-user>",
        "SMTP_PASSWORD": "<smtp-password>",
        "SMTP_FROM": "<smtp-from>"
      }
    }
  }
}

Settings → Developer → Edit Config (claude_desktop_config.json), then restart.

{
  "servers": {
    "smtp": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@ni-c/smtp-mcp"
      ],
      "env": {
        "SMTP_HOST": "<smtp-host>",
        "SMTP_USER": "<smtp-user>",
        "SMTP_PASSWORD": "<smtp-password>",
        "SMTP_FROM": "<smtp-from>"
      }
    }
  }
}

Add to .vscode/mcp.json in your workspace.

{
  "mcpServers": {
    "smtp": {
      "command": "npx",
      "args": [
        "-y",
        "@ni-c/smtp-mcp"
      ],
      "env": {
        "SMTP_HOST": "<smtp-host>",
        "SMTP_USER": "<smtp-user>",
        "SMTP_PASSWORD": "<smtp-password>",
        "SMTP_FROM": "<smtp-from>"
      }
    }
  }
}

Add to ~/.codeium/windsurf/mcp_config.json.

Configuration

Variable	Required	Secret	Description
SMTP_HOST	yes	—	Hostname of the SMTP server, e.g. smtp.example.net.
SMTP_PORT	—	—	Port. Defaults to 587 for starttls, 465 for implicit, 25 for none.
SMTP_TLS	—	—	starttls (default), implicit or none. STARTTLS is required, never opportunistic.
SMTP_USER	yes	—	Username for SMTP authentication.
SMTP_PASSWORD	yes	yes	Password or app-specific password for SMTP authentication.
SMTP_FROM	yes	—	The only sender this server will use, e.g. "Name <person@example.net>". There is no from parameter.
SMTP_REPLY_TO	—	—	Reply-To header on every message, e.g. "Team <team@example.net>". Unset means no Reply-To header and replies go to SMTP_FROM. There is no reply_to parameter.
SMTP_ALLOW_SEND	—	—	Set to "true" to register the sending tools. Defaults to false: the server cannot send until it is set.
SMTP_ALLOWED_RECIPIENTS	—	—	Comma-separated addresses and @domains this server may write to. Required with SMTP_ALLOW_SEND=true; "*" allows any.
SMTP_MAX_RECIPIENTS	—	—	Maximum distinct recipients across To, Cc and Bcc in one message. Default 10.
SMTP_MAX_SENDS_PER_HOUR	—	—	Sliding hourly cap on messages sent. Default 20.
SMTP_MAX_MESSAGE_BYTES	—	—	Maximum size of the composed message. Default 10485760.
SMTP_MAX_ATTACHMENT_BYTES	—	—	Maximum size of a single attachment. Default 5242880.
SMTP_ATTACHMENT_DIR	—	—	Directory attachments are read from. Unset means attachments are unavailable.
SMTP_ATTACHMENT_TYPES	—	—	Comma-separated content types that may be attached. Defaults to a document and image allowlist.
SMTP_SIGNATURE	—	—	Text appended below the standard signature delimiter of every message.
SMTP_AUDIT_LOG	—	—	File the audit lines are appended to, in addition to stderr.
SMTP_ALLOW_TOOLS	—	—	Comma-separated tool names, a prefix with one trailing *, or "essential" for the curated preset.
SMTP_DENY_TOOLS	—	—	Comma-separated tool names or prefixes to remove, applied after SMTP_ALLOW_TOOLS.
SMTP_INSECURE_TLS	—	—	Set to "true" to accept self-signed certificates. Prefer a proper internal CA.

Freshness

Active — last maintenance signal 3d ago. The newest of the signals below sets the band.

Last commit (default branch)
2026-10-06 · 3d ago · GitHub
Latest release
2026-09-07 · 32d ago · GitHub · v0.2.0
Package published
no data · npm/PyPI
Registry entry updated
2026-09-07 · 32d ago · official registry · v0.2.0

FAQ

›How do I install the SMTP MCP server in Claude Code?

Run: claude mcp add smtp -e SMTP_HOST='<smtp-host>' -e SMTP_USER='<smtp-user>' -e SMTP_PASSWORD='<smtp-password>' -e SMTP_FROM='<smtp-from>' -- npx -y @ni-c/smtp-mcp. For Cursor, VS Code, Claude Desktop and Windsurf, use the install tabs above.

›Does SMTP require an API key?

Yes. It expects SMTP_HOST, SMTP_USER, SMTP_PASSWORD, SMTP_FROM, of which 1 is a secret.

›Can I use SMTP as a remote (hosted) MCP server?

No hosted endpoint is published; it runs locally over stdio.

›Is SMTP in the official MCP registry?

Yes, as io.github.ni-c/smtp-mcp.