Postmark MCP Server
The official Postmark MCP server: 24 tools to send email, manage templates, search messages and diagnose delivery.
- 64 ★ on the repository
- Last commit
- MIT
Broad access
Why this level
- The agent sends real emails to customers from your domain, including in batches.
- The server token opens sending, templates, suppression lists and webhooks of the account.
Install
- Works in
In your terminal, with SkillFoxx CLI
npx skillfoxx add mcp/postmark-mcp-serverDetects the agents on your machine, shows the access level and pins the version.
Other ways to install
Access and checks
How we reviewBroad accessThe tool can change data, run commands or handle secrets.
- The agent sends real emails to customers from your domain, including in batches.
- The server token opens sending, templates, suppression lists and webhooks of the account.
This is third-party code. Review the repository files before installing.
What it does
Postmark MCP Server connects a Postmark account to Claude, Cursor and other MCP clients. The agent sends single and batch emails, including template-based ones, creates and validates templates, searches outbound messages and inspects delivery details. Separate tools analyze delivery failures, bounces and suppression lists, show statistics and server information, and register webhooks. All 24 tools carry `readOnlyHint` and `destructiveHint` annotations: clients that honor them auto-approve safe reads and ask confirmation for writes. Logs go to stderr as JSON, and email addresses are partially masked by default.
Who it is for. Developers and marketers with a Postmark account who want an agent to send transactional email and investigate delivery failures.
Good fit when
- An email to a customer did not arrive and you want the cause from the `diagnoseDelivery` tool.
- A template must be created, validated and edited without opening the Postmark console.
- Addresses with bounces must be found and reactivated through `activateBounce`.
- A batch of notifications must go out from a template with different data.
- Webhooks for opens, clicks and complaints must be registered at your HTTPS address.
Not a fit when
- There is no Postmark account: the server works only with its API and a server token.
- The agent reads untrusted emails and repositories: they may hide prompt injection while the tools can send mail.
- Node.js on the machine is older than 22 or lacks the latest patch: an update is needed because of a vulnerability.
Example request
Find emails to ivan@example.com from the last day, show the delivery status and the bounce reason if there was one.MCP
- Transport
- stdio
- Authentication
- API key
Environment variables
POSTMARK_SERVER_TOKENrequired, secret- Postmark server API token.
DEFAULT_SENDER_EMAILrequired- Default sender address verified in Postmark.
DEFAULT_MESSAGE_STREAMrequired- Postmark message stream, for example outbound.
WEBHOOK_URL_ALLOWLIST- Comma-separated HTTPS prefixes accepted for webhooks.
Limitations
Node.js 22 or newer on the latest patch, a Postmark account and a server token are required. The default sender address must be verified in Postmark. Open and click tracking is on for every send. Webhooks register over HTTPS only, and `WEBHOOK_URL_ALLOWLIST` sets the permitted prefixes. The `LOG_FILE` log is not rotated, so its size needs external limits. Prompt injection remains a threat: the server can send mail and register webhooks.
How to disable. Remove the `postmark` entry from the MCP client configuration. Revoke the server token in the Postmark console and delete registered webhooks with the `deleteWebhook` tool.
FAQ
How do I connect Postmark MCP Server without cloning?
Add a server to the client configuration with the `npx` command and arguments `-y @activecampaign/postmark-mcp`, and set `POSTMARK_SERVER_TOKEN`, `DEFAULT_SENDER_EMAIL` and `DEFAULT_MESSAGE_STREAM` in `env`. The same snippet works for Claude Desktop and Cursor.
Which environment variables are required?
Three: `POSTMARK_SERVER_TOKEN` with the server token, `DEFAULT_SENDER_EMAIL` with a verified sender address and `DEFAULT_MESSAGE_STREAM`, for example `outbound`. Others such as `LOG_FILE` are optional.
Which tools are available?
24 tools in eight groups: email, templates, messages, diagnostics, bounces, suppressions, statistics with server data, and webhooks. They include `sendEmail`, `sendBatch`, `searchOutboundMessages` and `diagnoseDelivery`.
How do I guard against prompt injection?
Do not let the agent read untrusted emails alongside this server and restrict webhooks with `WEBHOOK_URL_ALLOWLIST`. Clients that honor annotations will ask confirmation for sends and writes.
Is this the same server as the postmark-mcp package on npm?
The official package is `@activecampaign/postmark-mcp`, published by ActiveCampaign as the official Postmark server. Check the package name before installing: similar names may have a different author.
Discussion
No questions or reviews yet.
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Comparison with similar tools
Cards that share the main search query, and how they differ.
| Tool | Official | Authentication | Repository stars | Main difference |
|---|---|---|---|---|
| Postmark MCP Server (this card) | yes | API key | 64 | |
| email-mcp: an MCP server for IMAP and SMTP mail | no | key is optional | 158 | reads and sends mail over IMAP and SMTP; Postmark MCP Server works through a transactional email API with delivery diagnostics |
| Resend CLI | yes | 411 | the command line of the Resend service; this one is the MCP server of the Postmark service |
README in short
The repository belongs to the ActiveCampaign organization and is described as the official Postmark server. Smoke-test examples with read and write suites exist for development, while `npx` is the recommended launch for real use.