Postmark MCP Server

Postmarkサービスを介してメールを送信するためのMCPサーバーで、環境変数を通じて設定されます。

GitHub

ドキュメント

Official Postmark MCP Server

Send emails with Postmark using Claude and other MCP-compatible AI assistants.

Features

Exposes a Model Context Protocol (MCP) server backed by your Postmark account
24 tools spanning email sending (single + batch), templates (CRUD + validation), message search, delivery diagnostics, bounces, suppressions, stats, server info, and webhooks
Simple configuration via environment variables
Comprehensive error handling and graceful shutdown
Secure logging practices (no sensitive data exposure)
Automatic open/click tracking on every send

Useful Docs

📒 API Documentation
🔎 API Explorer
📖 Engineering Articles
📝 Changelog — what's new in each release

Feedback

We'd love to hear from you! Please share your feedback and suggestions using our feedback form.

Setup

Requirements

Node.js v20 or higher
A Postmark account and server token

Installation (Local Development)

Clone the repository:

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

Install dependencies:

npm install
# or
yarn
# or
bun install

Configuration (Local Development)

Create your own environment file from the example

cp .env.example .env

Edit your .env to contain your Postmark credentials and settings.

Important: This is intended for local development purposes only. Secrets should never be stored in version control and .env type files should be added to .gitignore.

Variable	Description	Required
POSTMARK_SERVER_TOKEN	Your Postmark server API token	Yes
DEFAULT_SENDER_EMAIL	Default sender email address	Yes
DEFAULT_MESSAGE_STREAM	Postmark message stream (e.g., 'outbound')	Yes

Run the server:

npm start
# or
yarn start
# or
bun start

Smoke test (requires valid .env):

The repo ships two smoke-test example files. Copy each to its non-example name (which is gitignored) before running, so your local edits — including any verified-sender addresses — never end up committed.

# Read-only suite (25 checks). Optionally edit RECIPIENT_WITH_HISTORY.
cp smoke-test.example.mjs smoke-test.mjs
npm run smoke

# Mutating suite (full lifecycles + real email sends).
# REQUIRED: edit SENDER and RECIPIENT to two of your verified addresses.
cp smoke-test-mutating.example.mjs smoke-test-mutating.mjs
node smoke-test-mutating.mjs

The read-only suite spawns the server over stdio and exercises every read tool against your Postmark account, plus the validation paths for editTemplate and createWebhook. Does not send mail or mutate state.

The mutating suite runs full create→edit→delete lifecycles for templates (including layout binding), webhooks, and suppressions, and sends real emails between the two addresses you configure. It cleans up after itself. The script refuses to run while the placeholder values are still in place.

Cursor Quick Install

After installing the MCP, update your configuration to set:

POSTMARK_SERVER_TOKEN
DEFAULT_SENDER_EMAIL
DEFAULT_MESSAGE_STREAM (default: outbound)

Claude and Cursor MCP Configuration Example

{
  "mcpServers": {
    "postmark": {
      "command": "node",
      "args": ["path/to/postmark-mcp/index.js"],
      "env": {
        "POSTMARK_SERVER_TOKEN": "your-postmark-server-token",
        "DEFAULT_SENDER_EMAIL": "[email protected]",
        "DEFAULT_MESSAGE_STREAM": "your-message-stream"
      }
    }
  }
}

Tools

This section provides a complete reference for the Postmark MCP server tools including example prompts and payloads. The server registers 24 tools organized into eight categories.

Email
Templates
Messages
- searchOutboundMessages
- getMessageDetails
Diagnostics
- diagnoseDelivery
Bounces
Suppressions
Stats & Server
- getDeliveryStats
- getServerInfo
Webhooks

Email

sendEmail

Sends a single text (and optional HTML) email.

Example Prompt:

Send an email using Postmark to [email protected] with the subject "Meeting Reminder" and the message "Don't forget our team meeting tomorrow at 2 PM."

Expected Payload:

{
  "to": "[email protected]",
  "subject": "Meeting Reminder",
  "textBody": "Don't forget our team meeting tomorrow at 2 PM.",
  "htmlBody": "<p>Don't forget our team meeting tomorrow at 2 PM.</p>",
  "from": "[email protected]",
  "tag": "meetings"
}

htmlBody, from, and tag are optional. If from is omitted, DEFAULT_SENDER_EMAIL is used.

Response:

Email sent successfully!
MessageID: 0a1b2c3d-...
To: [email protected]
Subject: Meeting Reminder

sendEmailWithTemplate

Sends an email using a Postmark template.

Example Prompt:

Send the "welcome" template to [email protected] with name "John Doe" and login_url "https://myapp.com/login".

Expected Payload:

{
  "to": "[email protected]",
  "templateAlias": "welcome",
  "templateModel": {
    "name": "John Doe",
    "login_url": "https://myapp.com/login"
  },
  "from": "[email protected]",
  "tag": "onboarding"
}

Provide either templateId (number) or templateAlias (string), not both.

Response:

Template email sent successfully!
MessageID: 0a1b2c3d-...
To: [email protected]
Template: welcome

sendBatch

Sends up to 500 emails in a single API call. Each message is fully independent (its own recipient, subject, body). This wraps Postmark's synchronous batch endpoint (POST /email/batch) — the call returns immediate per-message results — and synthesizes the success/failure summary. (Postmark also offers a separate asynchronous bulk email API at /email/bulk for large-volume jobs with submit-and-poll workflow, no message count cap, and a 50 MB payload limit. That's a parallel capability for different use cases — not currently wrapped by this MCP, tracked as a v2.1 follow-up.)

Expected Payload:

{
  "messages": [
    {
      "to": "[email protected]",
      "subject": "Order #1234 confirmed",
      "textBody": "Thanks Alice — your order is on its way.",
      "tag": "order-confirmation"
    },
    {
      "to": "[email protected]",
      "subject": "Order #1235 confirmed",
      "textBody": "Thanks Bob — your order is on its way.",
      "tag": "order-confirmation"
    }
  ]
}

Per-message fields: to, subject, textBody are required. htmlBody, from, cc, bcc, replyTo, and tag are optional. If from is omitted on a message, DEFAULT_SENDER_EMAIL is used.

Response:

Sent 2/2 successfully

Successes:
  - [email protected] — abc-123-def
  - [email protected] — abc-456-ghi

When some messages fail at submission (e.g., suppressed recipients), failures are listed first with their ErrorCode and reason:

Sent 8/10 successfully (2 failed)

Failures:
  - [email protected] — 406: Address has been suppressed.
  - [email protected] — 300: Inactive recipient
...

sendBatchWithTemplate

Sends up to 500 templated emails — same template, per-recipient template models. Ideal for "render this onboarding template for each new user" flows.

Expected Payload:

{
  "templateAlias": "welcome",
  "from": "[email protected]",
  "tag": "onboarding",
  "recipients": [
    { "to": "[email protected]", "templateModel": { "name": "Alice", "plan": "Pro" } },
    { "to": "[email protected]", "templateModel": { "name": "Bob", "plan": "Free" } }
  ]
}

Provide either templateId (number) or templateAlias (string). Top-level from and tag apply to all recipients but can be overridden per-recipient. Each recipient also accepts optional cc, bcc, and replyTo.

Response: same format as sendBatch.

Templates

listTemplates

Lists all templates on the server.

Response:

Found 2 templates:

• **Welcome**
  - ID: 12345678
  - Alias: welcome
  - Subject: Welcome to {{product_name}}

getTemplate

Retrieves a single template's full content (HTML body, text body, subject, type).

Payload: { "templateIdOrAlias": "welcome" } — accepts numeric ID or string alias.

createTemplate

Creates a new template. Requires name. At least one of htmlBody or textBody must be provided.

subject is required for Standard templates and must be omitted for Layout templates — Postmark rejects the field on Layouts.

layoutTemplate (Standard only) binds the new template to an existing Layout by alias. Without it, the new template renders unwrapped (no chrome from any layout).

Expected Payload:

{
  "name": "Order Confirmation",
  "subject": "Your order #{{order_id}} is confirmed",
  "htmlBody": "<h1>Thanks {{name}}</h1>",
  "textBody": "Thanks {{name}}",
  "alias": "order-confirmation",
  "templateType": "Standard",
  "layoutTemplate": "basic"
}

templateType may be "Standard" (default) or "Layout".

editTemplate

Updates an existing template. Requires templateIdOrAlias plus at least one updated field (name, subject, htmlBody, textBody, alias, or layoutTemplate).

Pass "layoutTemplate": null to unbind a template from its current Layout (the MCP translates this to the empty-string the Postmark API requires for clearing the association).

deleteTemplate

Deletes a template by ID or alias.

Payload: { "templateIdOrAlias": "order-confirmation" }

validateTemplate

Validates template content (Mustachio syntax, undefined variables) without saving. At least one of subject, htmlBody, or textBody is required.

Expected Payload:

{
  "subject": "Order #{{order_id}}",
  "htmlBody": "<p>Thanks {{name}}</p>",
  "textBody": "Thanks {{name}}",
  "testRenderModel": { "order_id": 42, "name": "John" },
  "templateType": "Standard"
}

Messages

searchOutboundMessages

Searches the outbound message history.

Expected Payload (all filters optional):

{
  "recipient": "[email protected]",
  "fromEmail": "[email protected]",
  "tag": "marketing",
  "subject": "Welcome",
  "status": "sent",
  "messageStream": "outbound",
  "fromDate": "2025-05-01",
  "toDate": "2025-05-15",
  "count": 50,
  "offset": 0
}

status is one of queued, sent, processed. count is 1–500 (default 50).

getMessageDetails

Retrieves full details and event timeline for a single outbound message.

Payload: { "messageId": "0a1b2c3d-..." }

Diagnostics

diagnoseDelivery

Composite triage tool. Answers "did my email reach X, and if not, why?" by running message search, suppression check, and bounce history lookups in parallel against a recipient address, then synthesizing a plain-English recommendation.

This is a diagnostic tool: it composes multiple Postmark API calls into a single coherent answer rather than mirroring a single endpoint.

Example Prompt:

Did my email to [email protected] get delivered? If not, what should I do?

Expected Payload:

{
  "recipient": "[email protected]",
  "messageId": "0a1b2c3d-...",
  "fromDate": "2026-04-21",
  "toDate": "2026-04-28",
  "messageStream": "outbound"
}

All fields except recipient are optional. If messageId is omitted, the most recent message to the recipient is used. The default search window is the last 7 days.

Sample response:

Delivery Diagnosis: [email protected]
────────────────────────────────────────────────

Suppression: not suppressed on stream "outbound"

Most recent message:
  MessageID: fadeae4e-fb04-4102-9303-9876078c7b81
  Subject:   Welcome to MyApp
  Sent:      2026-04-27T18:42:19.0000000-04:00
  Status:    Sent
  Events:    Delivered, Opened×2, Clicked

Bounce history: none

Recommended action:
  Email was delivered. If recipient says they didn't see it, check their
  spam folder or ask them to whitelist the sender domain.

When the recipient is suppressed, the recommendation differs based on reason: SpamComplaint is permanent, HardBounce may be reactivatable, ManualSuppression can be deleted via deleteSuppressions.

Bounces

searchBounces

Searches the bounce log with optional filters by type, recipient, tag, message ID, message stream, date range, and active/inactive status.

Expected Payload (all optional):

{
  "type": "HardBounce",
  "inactive": true,
  "emailFilter": "@example.com",
  "tag": "marketing",
  "messageID": "0a1b2c3d-...",
  "messageStream": "outbound",
  "fromDate": "2025-05-01",
  "toDate": "2025-05-15",
  "count": 50,
  "offset": 0
}

Supported type values (matches Postmark's BounceType enum — 22 values): AddressChange, AutoResponder, BadEmailAddress, Blocked, ChallengeVerification, DMARCPolicy, DnsError, HardBounce, InboundError, ManuallyDeactivated, OpenRelayTest, SMTPApiError, SoftBounce, SpamComplaint, SpamNotification, Subscribe, TemplateRenderingFailed, Transient, Unconfirmed, Unknown, Unsubscribe, VirusNotification.

getBounceDump

Returns the raw SMTP dump for a bounce. Bounce dumps are retained for 30 days.

Payload: { "bounceId": 123456 }

activateBounce

Reactivates a deactivated email address (only bounces where CanActivate: true).

Payload: { "bounceId": 123456 }

Suppressions

listSuppressions

Lists suppressions for a message stream.

Expected Payload (all optional):

{
  "messageStream": "outbound",
  "suppressionReason": "HardBounce",
  "origin": "Recipient",
  "emailAddress": "[email protected]",
  "fromDate": "2025-05-01",
  "toDate": "2025-05-15"
}

suppressionReason ∈ HardBounce, SpamComplaint, ManualSuppression. origin ∈ Recipient, Customer, Admin. If messageStream is omitted, DEFAULT_MESSAGE_STREAM is used.

createSuppressions

Suppresses up to 50 email addresses on a message stream.

Payload: { "emailAddresses": ["[email protected]", "[email protected]"], "messageStream": "outbound" }

deleteSuppressions

Removes up to 50 addresses from the suppression list. Note: SpamComplaint suppressions cannot be deleted.

Payload: { "emailAddresses": ["[email protected]"], "messageStream": "outbound" }

Stats & Server

getDeliveryStats

Unified stats tool. Default behavior returns a friendly headline summary; pass an optional stat for a focused breakdown.

Expected Payload (all optional):

{
  "stat": "summary",
  "tag": "marketing",
  "fromDate": "2025-05-01",
  "toDate": "2025-05-15",
  "messageStream": "outbound"
}

Supported stat values:

`stat`	What it returns
`summary` (default)	Headline open / click / bounce / spam rates
`overview`	All overview counts (sent, tracked, opens, clicks, bounces, …)
`sent`	Sent count
`bounces`	Bounce breakdown by type
`spam`	Spam complaint count
`tracked`	Tracked email count
`opens`	Total + unique opens
`openPlatforms`	Open platform breakdown (Desktop / Mobile / WebMail / Unknown)
`openClients`	Top 10 email clients (Apple Mail, Gmail, …)
`openReadTimes`	Read-time histogram
`clicks`	Total + unique link clicks
`clickBrowsers`	Top 10 browsers used to click
`clickPlatforms`	Click platform breakdown (Desktop / Mobile / WebMail / Unknown)
`clickLocation`	HTML vs. plain-text click location

Default summary response:

Email Delivery Summary

Sent:        74
Tracked:     33  (44.6% of sent)
Open rate:   93.9%  (31/33 unique opens)
Click rate:  4.8%  (10/207 unique links clicked)
Bounced:     1  (1.4%)
Spam:        0  (0.0%)

Period: 2025-05-01 → 2025-05-15
Tag: marketing

Sample stat: "openPlatforms" response:

Open Platform Usage

  Desktop        20  (64.5%)
  Mobile          0  (0.0%)
  WebMail        11  (35.5%)
  Unknown         0  (0.0%)

getServerInfo

Returns the Postmark server's name, color, tracking settings, and webhook URLs.

Payload: {}

Webhooks

listWebhooks

Lists configured webhooks. Optional messageStream filter.

createWebhook

Creates a webhook subscription. Requires a url and at least one trigger.

Expected Payload:

{
  "url": "https://example.com/postmark-hook",
  "messageStream": "outbound",
  "openEnabled": true,
  "clickEnabled": true,
  "deliveryEnabled": false,
  "bounceEnabled": true,
  "spamComplaintEnabled": true,
  "subscriptionChangeEnabled": false
}

deleteWebhook

Deletes a webhook by ID.

Payload: { "webhookId": 1234567 }

Implementation Details

API Request Headers

All requests to the Postmark API that are made directly by this server include the following headers for client identification and correlation:

Header	Description
`X-Postmark-Client`	Client identifier: `postmark-mcp`
`X-Postmark-Client-Version`	Version of this MCP server (matches package version)
`X-Postmark-Correlation-Id`	A unique ID per request (UUID v4) for correlating requests with your logs or support. The API may use this in the future; it is safe to send now.

These headers are sent on every request to the Postmark API. This server uses its own HTTP client (no postmark npm package) so that MCP traffic is identified as postmark-mcp and not as the Node.js SDK.

Automatic Configuration

All emails are automatically configured with:

TrackOpens: true
TrackLinks: "HtmlAndText"
Message stream from DEFAULT_MESSAGE_STREAM environment variable

Error Handling

The server implements comprehensive error handling:

Validation of all required environment variables
Graceful shutdown on SIGTERM and SIGINT
Proper error handling for API calls
No exposure of sensitive information in logs
Consistent error message formatting

Logging

Uses appropriate log levels (info for normal operations, error for errors)
Excludes sensitive information from logs
Provides clear operation status and results

For more information about the Postmark API, visit Postmark's Developer Documentation.

Postmark MCP Server

ドキュメント

Official Postmark MCP Server

Features

Useful Docs

Feedback

Setup

Requirements

Installation (Local Development)

Configuration (Local Development)

Cursor Quick Install

Claude and Cursor MCP Configuration Example

Tools

Table of Contents

Email

sendEmail

sendEmailWithTemplate

sendBatch

sendBatchWithTemplate

Templates

listTemplates

getTemplate

createTemplate

editTemplate

deleteTemplate

validateTemplate

Messages

searchOutboundMessages

getMessageDetails

Diagnostics

diagnoseDelivery

Bounces

searchBounces

getBounceDump

activateBounce

Suppressions

listSuppressions

createSuppressions

deleteSuppressions

Stats & Server

getDeliveryStats

getServerInfo

Webhooks

listWebhooks

createWebhook

deleteWebhook

Implementation Details

API Request Headers

Automatic Configuration

Error Handling

Logging

License