How to connect Mailersend to Claude Cowork

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Introduction

Cowork is Anthropic's AI agent for knowledge work. Think of it as Claude Code for everything else. It works autonomously with your computer, local files, and applications to accomplish complex tasks.

This guide walks you through the easiest and most secure way to connect your Mailersend account to Cowork via Composio Connect, enabling it to add a new sending domain for your app, list all SMTP users for our domain, check current API quota usage, and more such actions on your behalf without compromising your account security.

Also integrate Mailersend with

Connecting Mailersend to Claude Cowork

1. Open Customize

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

2. Add the Composio MCP server

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

3. 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 Cowork

4. Connect your Mailersend account

Back in Cowork, ask the agent to connect to Mailersend or give it any Mailersend-related task.

For example, ask Cowork to:

  • "Add a new sending domain for your app"
  • "List all SMTP users for our domain"
  • "Check current API quota usage"

It will prompt you to authenticate and authorize access.

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

What is Claude Cowork?

Claude Cowork is Anthropic's agent for general knowledge work. It can use your computer, files, and connected applications to complete longer-running tasks across your work tools.

With Composio Connect, Cowork can securely access apps like Mailersend through MCP without you sharing account credentials directly with the agent.

What is the Mailersend MCP server, and what's possible with it?

The Mailersend MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Mailersend account. It provides structured and secure access to your transactional email infrastructure, so your agent can perform actions like sending emails, managing domains, configuring webhooks, and monitoring API usage on your behalf.

  • Seamless domain management: Register new sending domains, verify their status, and retrieve detailed configuration information to ensure reliable email delivery.
  • Automated email and SMTP user setup: Quickly create SMTP users and API tokens as needed for secure and scalable application integration.
  • Webhook configuration and event tracking: Set up and delete webhooks to monitor real-time email events such as sent, delivered, or opened messages, enabling proactive workflows and notifications.
  • Recipient and quota insights: List recipients for specific domains and monitor your API usage to stay within account limits and optimize deliverability.
  • Centralized resource discovery: Retrieve general API resources and overview endpoints to streamline Mailersend integration and administration directly from your agent.

Supported Tools & Triggers

Tools
Create Sending DomainTool to add a new sending domain to mailersend.
Create SMTP UserTool to create a new smtp user.
Create API TokenTool to create a new api token.
Create WebhookTool to create a new webhook for a mailersend domain.
Delete WebhookTool to delete an existing webhook.
Get API QuotaTool to retrieve current api usage quota.
Get DomainTool to fetch information for a specific sending domain.
List Domain RecipientsTool to list recipients for a domain.
Get sending domainsTool to retrieve a list of sending domains.
Get general API resourcesTool to retrieve general api resources and information.
List Sender IdentitiesTool to list sender identities.
Get sent messagesTool to retrieve a paginated list of sent messages.
Get email recipientsTool to retrieve a list of email recipients.
Get SMS ActivityTool to retrieve sms activity logs.
Get SMS InboundsTool to retrieve inbound sms messages.
List SMS MessagesTool to list sent sms messages with optional filters.
Get SMS NumbersTool to retrieve a paginated list of sms phone numbers.
Get SMS recipientsTool to retrieve a list of sms recipients.
Get SMTP usersTool to retrieve a list of smtp users.
Get email templatesTool to retrieve a list of email templates.
Get API TokensTool to retrieve a list of api tokens.
Get usersTool to retrieve a list of users associated with your account.
List webhooksTool to retrieve a list of webhooks.

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FAQ

What are the differences in Tool Router MCP and Mailersend MCP?

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

Can I use Tool Router MCP with Claude Cowork?

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 Mailersend tools.

Can I manage the permissions and scopes for Mailersend while using Tool Router?

Yes, absolutely. You can configure which Mailersend 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.

How safe is my data with Composio Tool Router?

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 Mailersend data and credentials are handled as safely as possible.

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