Postmaster+ Agent Plugin

Email deliverability copilot that unifies Gmail Postmaster Tools, Outlook SNDS, Validity, universal feedback loops, and DNS into one health view — across all your teams.

An Agent Plugins package that connects any compatible AI client (Cursor, Claude, ChatGPT, and others) to the Postmaster+ deliverability platform over its hosted MCP server.

What is Postmaster+?

Postmaster+ is a deliverability assistant that aggregates signals from across the sender ecosystem — Gmail Postmaster Tools, Outlook SNDS, Validity, universal feedback loops, DNS, and more — into a single live view of your sender reputation and inbox placement. Start with a bird's-eye health overview, then drill into specifics: track domains and IPs, catch blocklisted IPs, surface inactive mail streams, and monitor complaint rates and mailbox-provider compliance over time. Natural-language questions resolve to the right data via intent-specific tools — count domains, chart multi-metric trends, or ask when Gmail compliance changed — and an actionable feed shows what needs attention across every team you can access. It also provisions agent-managed seedboxes: throwaway inbox addresses an agent can use to subscribe to a newsletter and verify deliverability without exposing your own domain or IP.

What this plugin provides

A single hosted MCP server (Streamable HTTP transport) exposing Postmaster+ tools to your agent:

• Overview & health — deliverability overview, actionable feed, unread counts
• Domains & IPs — list/count/inspect domains and IPs, timelines, complaint-rate history
• Reputation signals — Gmail compliance history, Gmail domain stats, ARF reports, spam identifiers
• Blocklists — list/count blocklisted IPs, start and check blocklist scans
• Mail streams — list mail streams, surface inactive ones
• Seedboxes — create/list/update/revoke agent-managed seedboxes, read messages, manage subscriptions and unsubscribes
• Teams — resolve and switch between every team you can access
• Email intelligence — on-demand intelligence scans

Installation

Cursor / Agent Plugins clients

Point the client at this repository, or add the MCP server directly:

{
  "$schema": "https://agent-plugins.org/schemas/1.0.0/mcp.schema.json",
  "mcpServers": {
    "postmaster": {
      "type": "streamable-http",
      "url": "https://postmasterplus.app/mcp/postmaster"
    }
  }
}

The server is authenticated with OAuth 2.0. Your client handles the sign-in flow on first connect — no API keys are embedded in this package. You will be asked to authorize the scopes your workflow needs:

• mcp:use — read deliverability data
• mcp:write — create, update, revoke, and delete resources
• mcp:spend — spend credits (seedboxes, blocklist and intelligence scans)

Package contents

postmasterplus-agent-plugin/
├── plugin.json   # Agent Plugins v1.0.0 manifest
├── mcp.json      # Hosted Postmaster+ MCP server (Streamable HTTP)
├── LICENSE
└── README.md

Links

• Product: https://postmasterplus.app
• Agent Plugins standard: https://agent-plugins.org