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How to connect Postgrid to Claude

Connect Claude Web, Desktop and Cowork to Postgrid MCP. Send a letter to new customer address, verify and standardize a shipping address, and more using natural language, with authentication handled for you.

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Postgrid is an API platform for automating direct mail and address verification. It helps businesses send mail and verify addresses instantly, reducing manual effort and errors.

60 Tools

Introduction

Claude is Anthropic's AI assistant, available on the web, in the desktop app, and on mobile. Cowork is its agent for knowledge work, and it runs on all of those surfaces too. Connected to your apps, Claude can work with your files and services to accomplish complex tasks on your behalf.

This guide walks you through the easiest and most secure way to connect your Postgrid account to Claude via Composio Connect, enabling it to send a letter to new customer address, verify and standardize a shipping address, create a reusable postcard template, and more such actions on your behalf without compromising your account security.

Setup is the same on Claude Web, Desktop, and Cowork, and you only need to do it once. The connector is tied to your account, so it's available in all three.

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Connecting Postgrid to Claude Web, Desktop, and Cowork

Two ways to add the Composio connector. Pick whichever you prefer.

1. Add with one click

Click the button. Claude opens with the Composio connector filled in. Click Add, then go to step 2.

Add to Claude

Add manually

In Claude Desktop, click Customize in the left sidebar, then select Connectors and click the + icon at the top.

Claude Desktop connectors screen with Add custom connector selected

Click Add custom connector and paste in the Composio MCP server URL:

bash
https://connect.composio.dev/mcp
Add custom connector dialog with Composio MCP server URL

2. Authorize in your browser

Click Connect. You'll be redirected to a browser window where you can authorize Composio to continue.

Composio authorization screen for Claude Web, Desktop, and Cowork

3. Connect your Postgrid account

Back in Claude, ask it to connect to Postgrid or give it any Postgrid-related task.

For example, ask Claude to:

  • "Send a letter to new customer address"
  • "Verify and standardize a shipping address"
  • "Create a reusable postcard template"

It will prompt you to authenticate and authorize access.

That's it. Composio's tools are now available in Claude, and your Postgrid account is ready to use.

What is the Postgrid Claude Connector, and what's possible with it?

The Postgrid MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Postgrid account. It provides structured and secure access to your direct mail and address automation tools, so your agent can verify addresses, send letters, manage contacts, and handle templates for your business communications—all without manual intervention.

  • Automated letter sending: Have your agent create and send physical letters on demand, handling recipient, sender, and content details seamlessly.
  • Contact management: Effortlessly add, update, or delete contacts in your Postgrid account to keep your mailing lists accurate and up to date.
  • Template creation and maintenance: Let your agent generate reusable mail templates with dynamic placeholders, and remove outdated templates as needed.
  • Bank account and payment management: Create or delete bank accounts associated with print and mail services, ensuring smooth financial operations for mail automation.
  • Webhook setup and monitoring: Enable your agent to create or remove webhooks to track events and receive real-time notifications for your mail orders and services.

Troubleshooting

1. Why does Claude not use the Composio connector for Postgrid?

The connector can show as connected, but Claude must use it in each Postgrid conversation.

  • Click + at the lower left of the chat, or type /.
  • Hover Connectors.
  • Turn on Composio.
  • Ask Claude to connect to Postgrid again.

2. Why does Claude show an MCP server error before Postgrid connects?

Claude can show Couldn't reach the MCP server or Authorization with the MCP server failed when you add the connector for Postgrid.

  • Check that the connector URL is https://connect.composio.dev/mcp.
  • Connectors run from Anthropic's cloud, so your device network is usually not the problem.
  • Add the connector again from Customize > Connectors, then ask Claude to connect Postgrid.
  • If it fails again, send the error and the ofid_ reference id to support@composio.dev.

3. Why does the Postgrid authorization link not work?

The Composio connector is one server. Your Postgrid account connects separately when Claude asks for it.

  • If the browser does not open, or the link expires, ask Claude to retry the Postgrid connection.
  • Composio creates a fresh Postgrid authorization link.
  • Open that link in your browser and finish the Postgrid sign-in.

4. Why do Postgrid actions fail after they worked before?

The Postgrid connection can expire or lose permission.

  • Ask Claude to inspect the Postgrid connection.
  • If the connection is unhealthy, disconnect it when Claude prompts you.
  • Reconnect the Postgrid account and retry the action.
  • If Claude shows a permission prompt, approve it before Claude changes data in Postgrid.
  • If the action still fails with a permission error, check that the connected account has that permission in Postgrid itself.

5. How do I switch to a different Postgrid account?

Claude can manage the Postgrid connection for you.

  • Ask Claude to disconnect or delete the current Postgrid account.
  • Ask Claude to connect Postgrid again.
  • Open the new Composio authorization link for Postgrid.
  • Sign in with the other Postgrid account in the browser.
  • After the account connects, ask Claude to retry the Postgrid task.

6. Why is my Postgrid connection missing in Claude Desktop or on a Team plan?

The connector belongs to your Claude account, so your Postgrid connection works in Claude Web, Desktop, and Cowork.

  • In Claude Desktop, open Customize > Connectors.
  • Next to Composio, click ⋮ and click Clear cache.
  • If Postgrid tools still do not appear, click ⋮, disconnect, remove the connector, and add it again.
  • On Team or Enterprise, an Owner or Primary Owner must enable the connector before you can connect Postgrid.
TOOLS

Supported Tools

Every Postgrid action and event your agent gets out of the box.

Cancel Box

Tool to cancel a box order by its ID.

Cancel Cheque

Tool to cancel a cheque order by its ID.

Cancel Cheque with Note

Tool to cancel a cheque order with a cancellation note.

Cancel Postcard

Tool to cancel a postcard order.

Cancel Postcard With Note

Tool to cancel a postcard order with an optional cancellation note.

Cancel Return Envelope Order

Tool to cancel a return envelope order.

CREATE_BANK_ACCOUNT

Tool to create a new bank account for print & mail service.

Create Box

Tool to create a box mailing order for letters with plastic cards or cheques.

Create Cheque

Tool to create a cheque order for physical cheque mailing.

Create Contact

Tool to create a new contact in PostGrid.

Create Letter

Tool to create and send a letter via PostGrid.

Create Postcard

Tool to create and send a postcard via PostGrid.

Create Return Envelope

Tool to create a return envelope for mail recipients to respond.

Create Return Envelope Order

Tool to create a batch order of return envelopes to be printed and delivered.

Create Template

Tool to create a new mail template in PostGrid.

Create Template Editor Session

Tool to create a template editor session for interactive template editing.

Create Tracker

Tool to create a tracker for monitoring mail delivery status via URL tracking.

Create Webhook

Tool to create a new webhook to receive order event notifications.

Delete Bank Account

Tool to delete a bank account by its ID.

Delete Contact

Tool to delete a contact by its ID.

Delete Template

Tool to delete a template by its ID.

Delete Template Editor Session

Tool to delete a template editor session by its ID.

Delete Tracker

Tool to delete a tracker by its ID.

Delete Webhook

Tool to delete a webhook subscription.

Fill Test Return Envelope Order

Tool to fill a test return envelope order for testing purposes.

Get Bank Account

Tool to retrieve a bank account.

Get Box

Tool to retrieve a specific box order by ID.

Get Cheque

Tool to retrieve a specific cheque by ID.

Get Contact

Tool to retrieve a contact.

Get Letter

Tool to retrieve a letter.

Get Postcard

Tool to retrieve a specific postcard by ID.

Get Return Envelope

Tool to retrieve a return envelope.

Get Return Envelope Order

Tool to retrieve a specific return envelope order.

Get Template

Tool to retrieve a template.

Get Tracker

Tool to retrieve a tracker.

Get Webhook

Tool to retrieve details of a specific webhook by its ID.

List Bank Accounts

Tool to list bank accounts.

List Box Orders

Tool to list box orders.

List Cheques

Tool to list cheques with optional filters and pagination.

List Contacts

Tool to list contacts.

List Webhook Events

Tool to retrieve a list of webhook events with optional pagination.

List Letters

Tool to list letters.

List Postal Statements

Tool to list all postal statements for billing and tracking purposes.

List Postcards

Tool to retrieve a list of postcards with optional filtering and pagination.

List Return Envelope Orders

Tool to list all return envelope orders for a specific return envelope.

List Return Envelopes

Tool to list return envelopes.

List Self-Mailers

Tool to list self-mailers.

List Sub-Organizations

Tool to list sub-organizations.

List Template Editor Sessions

Tool to list template editor sessions.

List Templates

Tool to list templates.

List Trackers

Tool to list all trackers.

List Tracker Visits

Tool to list all visits for a tracker.

List Webhook Invocations

Tool to list previous invocations of a webhook with response status codes.

List Webhooks

Tool to retrieve a list of configured webhooks with optional filtering and pagination.

Progress Test Box

Tool to progress a test box through processing stages for webhook testing.

Progress Test Cheque

Tool to progress a test cheque through processing stages for webhook testing.

Progress Test Postcard

Tool to progress a test postcard through processing stages for webhook testing.

Update Template

Tool to update an existing mail template in PostGrid.

Update Tracker

Tool to update an existing tracker's redirect URL template and/or expiration settings.

Update Webhook

Tool to update an existing webhook configuration.

FRAMEWORKS

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OpenAI Agents SDK logo

OpenAI Agents SDK

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Claude Agent SDK logo

Claude Agent SDK

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Claude Code logo

Claude Code

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Codex logo

Codex

Use Postgrid MCP with Codex

OpenClaw logo

OpenClaw

Use Postgrid MCP with OpenClaw

Hermes logo

Hermes

Use Postgrid MCP with Hermes

Atomic Agent logo

Atomic Agent

Use Postgrid MCP with Atomic Agent

Google ADK logo

Google ADK

Use Postgrid MCP with Google ADK

LangChain logo

LangChain

Use Postgrid MCP with LangChain

Vercel AI SDK logo

Vercel AI SDK

Use Postgrid MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Postgrid MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Postgrid MCP with LlamaIndex

CrewAI logo

CrewAI

Use Postgrid MCP with CrewAI

Pydantic AI logo

Pydantic AI

Use Postgrid MCP with Pydantic AI

AutoGen logo

AutoGen

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FAQ

Frequently asked questions

With a standalone Postgrid MCP server, the agents and LLMs can only access a fixed set of Postgrid tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Postgrid and many other apps based on the task at hand, all through a single MCP endpoint.

Yes, you can. Claude Cowork fully supports MCP integration. You get structured tool calling, message history handling, and model orchestration while Tool Router takes care of discovering and serving the right Postgrid tools.

Yes, absolutely. You can configure which Postgrid scopes and actions are allowed when connecting your account to Composio. You can also bring your own OAuth credentials or API configuration so you keep full control over what the agent can do.

All sensitive data such as tokens, keys, and configuration is fully encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant and follows strict security practices so your Postgrid data and credentials are handled as safely as possible.

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