Gmail Postmaster Tools MCP server

Gmail Postmaster Tools MCP

An MCP server for the Gmail Postmaster Tools API (v2) — query your domains, sender compliance status, and Gmail traffic metrics from Claude, Cursor, or any MCP client.

This is a bring-your-own-credentials tool for hands-on senders: you supply your own Google OAuth client, and the server runs the sign-in locally. Nothing is hosted and no data leaves your machine.

Want this without setting up a Google Cloud project? That's what

Postmaster+ is for — hosted, multi-provider

(Gmail + Outlook + more), with verification, history, and alerting.

Built & maintained by the Postmaster+ team at OptiPub.

What you get

• listdomains / getdomain — your registered domains and their verification state
• getcompliancestatus — SPF, DKIM, DMARC, alignment, message formatting, DNS records, TLS encryption, user-reported spam rate, and one-click / honored unsubscribe verdicts
• querydomainstats — spam rate, auth success (SPF/DKIM/DMARC), TLS encryption rate, delivery errors, and feedback-loop metrics over any date range
• gptauthenticate / gptauthstatus / gptsign_out

Note: Postmaster Tools v2 covers traffic metrics + compliance. Domain and

IP reputation are not part of v2.

Prerequisites: create a Google OAuth client (one-time, ~5 min)

You need a Google Cloud OAuth client because Google doesn't offer a shared public one for this API.

1. Go to the Google Cloud Console and create (or pick) a project.
2. APIs & Services → Library → search "Gmail Postmaster Tools API" → Enable.
3. APIs & Services → OAuth consent screen (redirects to Google Auth Platform). If the project has never been configured, click Get started and set an App name + support email, Audience = External, and a contact email. If it's already configured, you'll just see the tabs — skip to the next step.
4. Open the Audience tab. If User type = External, add your Google address under Test users → + Add users and Save (leave status as Testing — works without app verification, up to 100 users). If User type = Internal (a Workspace org project), no test users are needed — org users can sign in directly.
5. Open the Clients tab (or APIs & Services → Credentials) → Create client → application type Desktop app → Create.
6. Copy the Client ID and Client secret.

You'll paste those two values into this extension's configuration at install time. (Make sure the Google account you sign in with is one that has access in Gmail Postmaster Tools.)

Install in Claude / Cowork (the .mcpb)

The .mcpb is a packaging convenience for Claude Desktop / Cowork only.

1. Download gmail-postmaster-tools.mcpb from the latest release.
2. Settings → Capabilities → install extension, pick the file.
3. When prompted, paste your Google OAuth Client ID and Client Secret.
4. Run gpt_authenticate once — your browser opens for the Google sign-in.

Use with other MCP clients (Cursor, VS Code, Windsurf, …)

Underneath, this is a standard stdio MCP server — any client that runs local MCP servers can use it directly, no .mcpb required. Clone or download the repo, then point the client at server/index.js and pass your Google credentials as env vars.

Shortened. The full README is on GitHub.