What is postmark-mcp CLAUDE.md?

A project guide for an AI coding assistant working on a Postmark integration. Postmark is an email service, and the guide documents the project, its commands, structure, and available tools.

Use it to start the server, inspect its Model Context Protocol tools, and run read-only or full lifecycle tests for templates, webhooks, suppressions, and email sending.

It gives the assistant the project context needed to work consistently and explains how to run checks and inspect the integration.

How ActiveCampaign/postmark-mcp configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to ActiveCampaign/postmark-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/ActiveCampaign/postmark-mcp/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/ActiveCampaign/postmark-mcp

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/activecampaign/postmark-mcp/claude-md/github.svg)](https://agentmods.dev/instructions/activecampaign/postmark-mcp/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/activecampaign/postmark-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/activecampaign/postmark-mcp/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/activecampaign/postmark-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/activecampaign/postmark-mcp/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 2,030 This file is loaded in full into every session.

When invoked 2,030 The same file — it is already loaded in full.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.02030	$0.02030
Opus 5.5	$0.00812	$0.00812
Sonnet 5.5	$0.00406	$0.00406
Haiku 4.5	$0.00203	$0.00203

Measured 2mo ago against content hash aded6c254c06, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

postmark-mcp CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

CLAUDE.md · 74 lines

How it starts

The opening of the file, as written. The whole thing — 74 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

Official Postmark MCP (Model Context Protocol) server that enables AI assistants (Claude, Cursor, etc.) to interact with the Postmark email API. Published as @activecampaign/postmark-mcp on NPM.

Commands

Run server: npm start (runs node index.js)
Debug with MCP Inspector: npm run inspector (launches @modelcontextprotocol/inspector)
Smoke test (read-only): npm run smoke — runs smoke-test.mjs, which is created from smoke-test.example.mjs. Spawns the server over stdio and exercises every read-only tool against the live Postmark account configured in .env. Does not send mail or mutate state.
Smoke test (mutating): node smoke-test-mutating.mjs — runs full create→edit→delete lifecycles for templates (including layout binding), webhooks, and suppressions, plus real email sends between two configured verified addresses. Cleans up after itself. Created from smoke-test-mutating.example.mjs; edit SENDER and RECIPIENT before running. The script refuses to run with the placeholder values still in place.
smoke-test.mjs and smoke-test-mutating.mjs are gitignored. Copy from the *.example.mjs counterparts; this keeps personal verified-sender addresses out of the repo.
No linter is configured.

Architecture

This is a single-file MCP server (index.js) using ES modules ("type": "module"). The structure within index.js:

Module-level formatting helpers — fmtInt, fmtPct, fmtPlatformUsage, fmtTopBreakdown, fmtDeliverySummary, fmtStatResponse. Used by getDeliveryStats to render polished per-stat output. Keep these pure / dependency-free.
initializeServices() — Validates required env vars, verifies connectivity via a postmarkRequest('/server') call, and instantiates McpServer from @modelcontextprotocol/sdk
registerTools(server) — Registers all 24 MCP tools with Zod schemas for input validation. Each tool wraps a postmarkRequest call and returns formatted text responses
main() — Orchestrates initialization, tool registration, and connects to StdioServerTransport

Read the full file on GitHub · 74 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 74 lines · 2,030 tokens per session scan A aded6c254c06

Subscribe to this mod's changes

postmark-mcp CLAUDE.md is an instructions file published in the GitHub repository ActiveCampaign/postmark-mcp (60 stars, last pushed 11d ago), licensed MIT. It adds 2,030 tokens to every session, about $0.0081 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Backend and APIs activecampaign ai email email-sender mcp postmark

postmark-mcp CLAUDE.md next to 6 instructions from other repositories
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postmark-mcp: Instructions file for Claude Code