Koskamo

mailfloss MCP

This official server exposes the mailfloss v1 REST API as tools for AI agents, enabling email verification, batch list processing, account credit checks, and integration management within MCP clients like Claude or Cursor.

Endpoint and access

OAuth sign-in: the first time you connect, your client opens the vendor's own authorization prompt in a browser.

mailfloss MCP logo, by mailflossVendor evidenceStreamable HTTPOAuth sign-inEndpoint checked 2026-10-26Operated by mailfloss
You need:sign in to the mailfloss dashboardCreate a key in the mailfloss dashboard under Developers → API keys
MCP endpoint (Streamable HTTP)
https://api.mailfloss.com/mcp
Vendor documentation

What you can do with it

  • Verify a single email address before adding it to a list
  • Run batch verification on a list of 40 addresses
  • Check remaining account credits for the month
  • Test if a Klaviyo integration connection is working

Source and maintenance

Vendor evidenceRegistry 1.0.0
mcp-registry: com.mailfloss/mailfloss@1.0.0Project website

Tools

Reported by the attributed source; not independently observed by Koskamo.

No tool definitions available.

Maintenance history

Public check and source-refresh events. Editorial and ownership records remain private.

  • · registry · passed · metadata changed · Source metadata updated
  • · backfill · recorded · Pre-expansion baseline; unobserved rich metadata remains unknown

Connect from your client

Each snippet registers the same endpoint; pick the client you use.

This server is operated by the named third party. Listing and endpoint checks are not an endorsement or a security audit. Review the operator's permissions, terms, and data handling before connecting. How listings are checked and corrected.

Claude Code

Run this once in a terminal. It registers the remote server. Use --scope project to write .mcp.json for the repo.
Claude Code configuration
claude mcp add --transport http mailfloss-mcp https://api.mailfloss.com/mcp

Codex

Run this once. Codex stores MCP servers in ~/.codex/config.toml (or .codex/config.toml in a trusted project).
Codex configuration
codex mcp add mailfloss-mcp --url https://api.mailfloss.com/mcp

Cursor

Merge this server into .cursor/mcp.json in your project, then enable mailfloss-mcp in your MCP settings.
Cursor configuration
{
  "mcpServers": {
    "mailfloss-mcp": {
      "url": "https://api.mailfloss.com/mcp"
    }
  }
}

Cline

Merge this into cline_mcp_settings.json (Cline → MCP Servers → Configure).
Cline configuration
{
  "mcpServers": {
    "mailfloss-mcp": {
      "type": "streamableHttp",
      "url": "https://api.mailfloss.com/mcp",
      "disabled": false
    }
  }
}

VS Code

Merge this server into .vscode/mcp.json. Use MCP: List Servers to start mailfloss-mcp and inspect its tools.
VS Code configuration
{
  "servers": {
    "mailfloss-mcp": {
      "type": "http",
      "url": "https://api.mailfloss.com/mcp"
    }
  }
}

Gemini CLI

Run this once. It writes .gemini/settings.json in the current project; pass --scope user for ~/.gemini/settings.json.
Gemini CLI configuration
gemini mcp add --transport http mailfloss-mcp https://api.mailfloss.com/mcp

Claude Desktop

Merge this into claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/, Windows: %APPDATA%\Claude\), then restart Claude Desktop.
Claude Desktop configuration
{
  "mcpServers": {
    "mailfloss-mcp": {
      "url": "https://api.mailfloss.com/mcp"
    }
  }
}

Windsurf

Merge this into ~/.codeium/windsurf/mcp_config.json, then refresh MCP in Cascade. Windsurf remote servers use serverUrl, not url.
Windsurf configuration
{
  "mcpServers": {
    "mailfloss-mcp": {
      "serverUrl": "https://api.mailfloss.com/mcp"
    }
  }
}

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Do you run mailfloss MCP?

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