How to integrate Mailtrap MCP with Grok Build

Connect Grok Build to Mailtrap MCP. Send a test email to marketing team, list all emails sent from mailtrap today, and more from your terminal, with authentication handled for you.

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Mailtrap is an email delivery platform for safe email testing and transactional email sending. It helps you catch bugs and verify email flows without spamming real inboxes.

49 Tools

How to integrate Mailtrap MCP with Grok Build

Grok Build is xAI's terminal coding agent. It runs on Grok 4.5, plans its work before it acts, and can run multiple sub-agents in parallel. It also reads Claude Code's MCP configuration, so any server you already have in a .mcp.json is picked up with no changes.

In this guide, I will show you how to connect your Mailtrap account to Grok Build through Composio, so it can send a test email to marketing team, list all emails sent from Mailtrap today, create a new inbox for transactional testing, and more without leaving the terminal. Composio holds the OAuth tokens for you, and Grok Build only calls the tools you approve.

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Why use Composio over a standalone MCP server?

  • Read and write access. Composio's Mailtrap integration lets Grok Build take real actions like creating drafts, sending updates, and labeling records, not just reading data.
  • 1,000+ SaaS toolkits out of the box. One endpoint gives you a full catalog of pre-built connectors, from Gmail and Slack to Notion, Linear, and Salesforce.
  • One MCP server for every app. Wire up a single Composio server instead of maintaining a separate MCP entry for each app.
  • Smart, context-aware tool loading. Grok Build caps how many tools it holds in a single request. Composio loads only the tools a task needs, so you do not spend that budget on tools you are not using.
  • Cross-app automation. Chain actions across apps in one run. Pull a thread, summarize it in Notion, and post the highlights to Slack from a single prompt.

Prerequisites

  • Grok Build installed and signed in. Install with curl -fsSL https://x.ai/cli/install.sh | bash on macOS or Linux, or irm https://x.ai/cli/install.ps1 | iex on Windows PowerShell. On first launch Grok opens a browser to authenticate; for headless or CI use, set an XAI_API_KEY environment variable instead (create the key at console.x.ai).
  • Access to the Mailtrap account you want to connect.
  • The Composio MCP endpoint. Composio's server is remote and hosted, so there is nothing to run locally and no tunnel to set up.

Step-by-step: Connect Mailtrap to Grok Build

1. Install and verify Grok Build

Install the CLI, then restart your shell so the grok binary lands on your PATH:

bash
curl -fsSL https://x.ai/cli/install.sh | bash
which grok

On Windows, install with PowerShell instead: irm https://x.ai/cli/install.ps1 | iex. If which grok returns a path, you are set. Grok Build runs on Grok 4.5 by default; you can switch models inside the session with /model <name>.

2. Add the Composio server

Add Composio as a remote HTTP MCP server with the grok mcp add command:

bash
grok mcp add --transport http composio https://connect.composio.dev/mcp

You can also add and manage servers from inside a session. Run /mcps to open the extensions modal on the MCP tab, then add a new server and paste the Composio URL. Added this way, Grok auto-detects the name from the URL and lists the server as connect:

bash
https://connect.composio.dev/mcp
Grok Build /mcps extensions modal listing MCP servers Grok Build adding the Composio MCP server with its URL

Grok also reads Claude Code-style config, so an entry in ~/.grok/config.toml or a project .mcp.json works the same way.

3. Authenticate

Composio uses OAuth. In the /mcps modal, select the Composio server and press i to authenticate (Grok also triggers this browser flow automatically the first time it uses a Composio tool). Click Allow to authorize access. Grok stores the tokens under ~/.grok/mcp_credentials.json, and /mcps shows Composio as connected.

Grok Build prompting to authenticate the Composio MCP server Composio authorization screen with the Allow button for Grok Build

4. Start building

Ask Grok to work with your Mailtrap account through Composio. On the first Mailtrap action, Composio prompts you to connect the account through OAuth. Approve the scopes once, and Composio handles token refresh from there.

What you can do after connecting Mailtrap

  • Send a test email to marketing team
  • List all emails sent from Mailtrap today
  • Create a new inbox for transactional testing

Security + privacy notes (important)

  • Use least-privilege access. Grant only the Mailtrap scopes you actually need.
  • Review OAuth scopes before approving. Check that the requested scopes match what you expect Composio and Grok Build to do.
  • Keep write actions human-reviewed. Grok Build proposes a plan before it acts. Leave that approval step on for actions like sending messages or editing records.
  • Keep secrets out of version control. Your XAI_API_KEY and any tokens should never be committed. Use environment variables or a secrets manager.
TOOLS

Supported Tools

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

Clean Inbox

Tool to clean an inbox in Mailtrap by deleting all messages.

Create Contact

Tool to create a new contact in Mailtrap.

Create Contact Event

Tool to create a contact event in Mailtrap.

Create Contact Export

Tool to create a contact export job for a Mailtrap account.

Create Contact Field

Tool to create a custom contact field in Mailtrap.

Create Contact List

Tool to create a new contact list in Mailtrap.

Create Email Template

Tool to create a new email template in Mailtrap account.

Create Sending Domain

Tool to create a new sending domain in Mailtrap.

Delete Contact

Tool to delete a contact from a Mailtrap account.

Delete Contact Field

Tool to delete a contact field by its ID.

Delete Contact List

Tool to delete a contact list by its ID.

Delete Email Template

Tool to delete an email template from a Mailtrap account.

Delete Project

Tool to delete a project from Mailtrap.

Delete Sending Domain

Tool to delete a sending domain from a Mailtrap account.

Get Billing Usage

Tool to retrieve current billing cycle usage for an account.

Get Contact

Tool to retrieve a contact by UUID or email address from Mailtrap.

Get Contact Export

Tool to retrieve the status of a contact export.

Get Contact Field

Tool to retrieve contact field details by field ID.

Get Contact Import Status

Tool to retrieve the status of a contact import operation.

Get Contact List

Tool to retrieve a specific contact list by its ID.

Get Email Template

Tool to retrieve details of a specific email template by ID.

Get Inbox Attributes

Tool to retrieve inbox attributes from Mailtrap.

Get Message HTML Body

Tool to retrieve the HTML body of a message from Mailtrap.

Get Permission Resources

Tool to retrieve all resources in account for permission management.

Get Project by ID

Tool to retrieve project details from Mailtrap by project ID.

Get Sending Domain

Tool to retrieve sending domain details from Mailtrap.

Get Sending Stats

Tool to retrieve email sending statistics from Mailtrap for a specific account.

Get Sending Stats by Categories

Tool to retrieve email sending statistics grouped by categories.

Get Sending Stats by Date

Tool to retrieve email sending statistics aggregated by date.

Get Sending Stats by Domains

Tool to retrieve sending statistics grouped by domains for a Mailtrap account.

Get Sending Stats by ESP

Tool to retrieve email sending statistics grouped by email service providers (ESPs) for a specified date range.

Import Contacts

Tool to import contacts in bulk to Mailtrap.

List Accounts

Tool to list all Mailtrap accounts you have access to.

List Contact Fields

Tool to get all contact fields for a Mailtrap account.

List Contact Lists

Tool to retrieve all contact lists for a Mailtrap account.

List Email Templates

Tool to retrieve all email templates for a Mailtrap account.

List Inboxes

Tool to get a list of inboxes for a Mailtrap account.

List Messages in Inbox

Tool to get messages from a Mailtrap inbox.

List Projects

Tool to get a list of projects for a Mailtrap account.

List Sending Domains

Tool to list all sending domains for a Mailtrap account.

List Email Suppressions

Tool to list suppressed email addresses for a Mailtrap account.

Mark Inbox as Read

Tool to mark all messages in a Mailtrap inbox as read.

Reset Inbox Credentials

Tool to reset SMTP credentials for a Mailtrap inbox.

Update contact

Tool to update an existing contact in Mailtrap.

Update Contact Field

Tool to update a contact field in Mailtrap.

Update Contact List

Tool to update a contact list's name in Mailtrap.

Update Email Template

Tool to update an existing email template in Mailtrap account.

Update inbox

Tool to update an inbox's settings in Mailtrap.

Update project

Tool to update a project's name in Mailtrap.

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FAQ

Frequently asked questions

A standalone Mailtrap MCP server gives Grok Build a fixed set of Mailtrap tools tied to that one server. The Composio Tool Router lets Grok Build load tools from Mailtrap and many other apps on demand, based on the task, all through a single endpoint.

Yes. Grok Build ships with native MCP support. Add a server with the grok mcp add command, from the in-session /mcps modal, or by editing ~/.grok/config.toml. It also reads Claude Code-style .mcp.json files, so Grok Build discovers the tools automatically.

Yes. Grok Build has zero-migration compatibility with Claude Code's configuration, so the same Composio server entry works in both without edits.

Tokens, keys, and configuration are encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant, so your Mailtrap data and credentials are handled to that standard.

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