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AI agents

Let your AI agent send the email

PostStack ships a Model Context Protocol server, so an agent can look up a contact, render a template, check the result and send — through the same pipeline, suppressions and limits as your API.

Get started freeRead the mcp server docs
  • 3,000 emails a month free
  • No credit card
  • Hosted in Finland
  • REST, SMTP and MCP

A real MCP server

Connect Claude, Cursor or any MCP client. The agent gets tools for emails, contacts, templates, broadcasts, domains and webhooks, plus prompts that tell it which tools to use in which order.

Scoped access

Give an agent a key restricted to one domain, or a test key that never reaches a mail server, so it can practise before it sends for real.

The same guard rails

Agent sends go through the same suppression list, rate limits and DKIM signing as API sends. Nothing about an agent bypasses your sender reputation.

What agents do with it

Personal welcome emails
“Send ada@lovelace.io a welcome email” — the agent finds the contact, picks the template, fills the variables and lints the result before sending.
Follow up on a campaign
Ask which recipients of last week’s broadcast did not click, and draft a follow-up to just them.
Answer inbound mail
Read a received email, draft a reply in the thread, and leave it for a human to approve or send it directly.
Set up a domain
Add a domain, read back the DNS records to publish, and check verification — from your editor.

Add PostStack to your MCP client

json
{
  "mcpServers": {
    "poststack": {
      "command": "npx",
      "args": ["-y", "@poststack.dev/mcp"],
      "env": { "POSTSTACK_API_KEY": "sk_test_..." }
    }
  }
}

Set it up in three steps

  1. 1

    Create a test key

    An sk_test_ key runs every check and fires webhooks without delivering anything.

  2. 2

    Connect your client

    Add the server to Claude, Cursor or another MCP client, locally or over the hosted endpoint.

  3. 3

    Ask for an email

    Describe what you want sent. Switch to a live key when you trust what the agent does.

What you’ll use

Email APISend transactional email from EU infrastructure with a single API call. Official TypeScript, Python, and Go SDKs, plus REST examples for every major language.Dynamic email templatesReusable email templates with {{variables}} and conditional blocks. Build them in the visual builder or paste your own HTML, publish, and send by ID — copy changes never need a redeploy.Contact management and segmentsStore contacts with typed custom properties, import them from CSV, and build rule-based segments for targeted email. Subscription topics and RFC 8058 one-click unsubscribe are handled for you.Email broadcastsSend newsletters and announcements to a segment of your contacts from the dashboard, the API, or an AI agent. Schedule sends, A/B test subject lines and content, and track results per campaign.

In the docs

Frequently asked questions

What is MCP?

The Model Context Protocol is an open standard that lets an AI client call tools a server exposes. PostStack’s MCP server exposes its email API as tools, so an agent can send email without you writing glue code.

Which AI clients work with it?

Any client that speaks MCP — Claude Desktop, Claude Code, Cursor and others. You can run the server locally with npx or connect to the hosted endpoint.

How do I stop an agent from emailing the wrong people?

Start with a test key so nothing is delivered, restrict live keys to the domain the agent should send from, and rely on the suppression list: unsubscribed and bounced addresses are skipped for agent sends exactly as for API sends.

Does it cost extra?

No. MCP is included on every plan, and agent sends count toward your monthly allowance like any other email. 3,000 emails a month free, no credit card.

More use cases

Transactional emailPassword resets, receipts, magic linksNewslettersBroadcasts to segments, unsubscribe built inSaaS productsOnboarding, product email and your customers’ domainsE-commerceOrder confirmations, shipping and receiptsBusiness emailMailboxes on your domain, €1 a monthGDPR-compliant emailEU hosting, a DPA and no CLOUD Act

Send your first email today

3,000 emails a month free, forever. No credit card, and about five minutes from sign-up to the first message in your inbox.

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