SMTP2GO MCP

https://developers.smtp2go.com/mcp is a remote Streamable HTTP MCP server. It initializes as SMTP2GO-API-Docs and exposes tools for listing/searching API endpoints plus executing API requests.

The documentation discovery tools may be available without authentication. API execution through execute-request requires an SMTP2GO API key in the X-Smtp2go-Api-Key request header.

Prerequisites

For clients that use mcp-remote, install Node.js/npm first. The first run may download mcp-remote through npx.

Set it for your current terminal session:

export SMTP2GO_API_KEY="your-smtp2go-api-key"

If your MCP client supports environment variables or a secret manager, prefer that over storing keys in project files. For local shell-driven clients, you can add the key to your shell profile, such as ~/.zshrc:

echo 'export SMTP2GO_API_KEY="your-smtp2go-api-key"' >> ~/.zshrc
source ~/.zshrc

Codex App / Codex CLI

In the Codex App, go to Settings > Configuration and open config.toml. If you use Codex CLI, the config file is usually:

~/.codex/config.toml

Add:

[mcp_servers.smtp2go]
command = "npx"
args = ["-y", "mcp-remote", "https://developers.smtp2go.com/mcp", "--header", "X-Smtp2go-Api-Key: ${SMTP2GO_API_KEY}"]
enabled = true

[mcp_servers.smtp2go.env]
SMTP2GO_API_KEY = "your-real-smtp2go-api-key"

This runs mcp-remote as a local stdio MCP server and injects the required X-Smtp2go-Api-Key HTTP header when proxying requests to the remote SMTP2GO MCP server.

In Codex and other shell-driven clients, the header value can include a space after the colon:

X-Smtp2go-Api-Key: ${SMTP2GO_API_KEY}

Claude Code

claude mcp add --transport http smtp2go https://developers.smtp2go.com/mcp \
  --header "X-Smtp2go-Api-Key: $SMTP2GO_API_KEY"

Gemini CLI

gemini mcp add smtp2go https://developers.smtp2go.com/mcp \
  --transport http \
  --header "X-Smtp2go-Api-Key: $SMTP2GO_API_KEY"

Cursor

In Cursor, go to Settings > Tools and MCPs > New MCP Server, then paste:

{
  "mcpServers": {
    "smtp2go": {
      "type": "streamable-http",
      "url": "https://developers.smtp2go.com/mcp",
      "headers": {
        "X-Smtp2go-Api-Key": "${SMTP2GO_API_KEY}"
      }
    }
  }
}

Claude Desktop

If Claude Desktop does not support remote HTTP directly, use mcp-remote:

Open Claude Desktop, go to Settings > Developer > Edit Config, and edit claude_desktop_config.json. On macOS this file is usually:

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

{
  "mcpServers": {
    "smtp2go": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote@latest",
        "https://developers.smtp2go.com/mcp",
        "--header",
        "X-Smtp2go-Api-Key:${SMTP2GO_API_KEY}"
      ],
      "env": {
        "SMTP2GO_API_KEY": "your-real-smtp2go-api-key"
      }
    }
  }
}

Claude Desktop launches MCP servers directly, not through your shell, so values exported in ~/.zshrc may not be available. Put SMTP2GO_API_KEY in the server env block, then reference it with ${SMTP2GO_API_KEY} in args. The header intentionally has no space after X-Smtp2go-Api-Key: to avoid argument escaping issues in desktop MCP clients.

Save claude_desktop_config.json, then fully quit and restart Claude Desktop.

Lovable

In Lovable, open https://lovable.dev/dashboard, then go to Connectors.

Under Chat connectors, select Custom MCP. It is usually the last item in the Chat connectors list.

Fill in the form:

Server name: SMTP2GO
Server URL: https://developers.smtp2go.com/mcp
Authentication: Bearer token or API key

Enter your SMTP2GO API key, then select Add server.

Lovable chat may ask for the API token again when it adds email integrations. If prompted, enter the same SMTP2GO API key.

When you ask Lovable to send email through SMTP2GO, explicitly instruct it to use a verified sender email address. Sending may fail if the sender address is not verified in your SMTP2GO account.

Confirm it works

After configuring the server, your MCP client should show these tools:

list-endpoints
get-endpoint
search-endpoints
execute-request

Try a read-only discovery action first, such as searching for email/send or listing endpoints, before using execute-request.

Authentication Notes

https://app.smtp2go.com/sending/apikeys/

These permissions are recommended for email sending:

/email/send
/allowed_senders/view
/domain/view

Then configure your MCP client to send the key with API execution requests as:

X-Smtp2go-Api-Key: your-smtp2go-api-key

For simplicity, most MCP client examples above send the header on every MCP request.

Do not commit real API keys to project configuration. Prefer a dedicated, narrowly scoped SMTP2GO API key for MCP use, and use environment variable expansion or a secret manager where your MCP client supports it.

execute-request can perform real SMTP2GO API actions, including sending email if the key has permission. Remove or disable the key when it is no longer needed.