How to Give Claude Code an Email in 60 Seconds

Claude Code is remarkably capable. It can write code, run tests, deploy applications, and debug complex systems. But the moment it needs to send a confirmation email, receive a webhook response from a third party, or communicate with a human outside the terminal, it hits a wall.

The fix takes about 60 seconds. Here is how to give Claude Code its own email address using MailboxKit.

Why Claude Code Needs Email

Think about the workflows where email becomes a bottleneck. Your AI coding agent is building a user registration flow and needs to test the welcome email. It is integrating with a service that sends verification codes via email. It needs to notify you when a long-running deployment finishes.

Without email access, Claude Code has to stop and ask you to handle these steps manually. With its own inbox, it handles the entire workflow autonomously.

Step 1: Get Your API Key

Sign up at mailboxkit.com and grab your API key from the dashboard. No credit card required to start. You get $1.00 in free credits, enough for 500 emails.

Your API key looks like mbk_live_a1b2c3d4... and authenticates all requests as a Bearer token.

Step 2: Create an Inbox

Open your terminal and create an inbox with a single curl command:

curl -X POST https://mailboxkit.com/api/v1/inboxes \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"name": "Claude Code"}'

The response gives you an inbox ID and a real, working email address like abc123@agent.mailboxkit.com. It can send and receive messages immediately.

Step 3: Create the SKILL.md File

This is where it gets interesting. Claude Code reads markdown instruction files to learn new capabilities. Create a file called SKILL.md in your project root:

# Email Skill

You have access to a working email inbox via the MailboxKit API.

## Configuration
- API Base URL: https://mailboxkit.com/api/v1
- API Key: mbk_live_YOUR_KEY_HERE
- Inbox ID: 3
- Email Address: abc123@agent.mailboxkit.com

## Send an Email
POST /api/v1/inboxes/{inbox_id}/messages/send
Headers: Authorization: Bearer <api_key>
Content-Type: application/json
Body: {"to": ["recipient@example.com"], "subject": "Subject", "text": "Body"}

## Check Inbox
GET /api/v1/inboxes/{inbox_id}/messages
Headers: Authorization: Bearer <api_key>

## Reply to a Message
POST /api/v1/inboxes/{inbox_id}/messages/{message_id}/reply
Body: {"text": "Reply body"}

Replace the placeholder values with the real credentials from Steps 1 and 2. Drop this file into your project directory, and Claude Code now knows how to use email.

A Practical Example

Say you are building a SaaS app and you ask Claude Code to implement the full signup flow including email verification. Here is what happens with the SKILL.md in place:

1. Claude Code writes the registration endpoint and email verification logic.
2. It sends a test signup request to the local server.
3. The server dispatches a verification email to the MailboxKit inbox.
4. Claude Code checks its inbox, finds the verification email, extracts the confirmation link.
5. It hits the confirmation endpoint and verifies the entire flow works end to end.

No manual intervention. No copy-pasting verification codes. The agent tested the complete user journey on its own.

Deployment Notifications

Add a simple instruction to your SKILL.md:

## Notification Rule
After completing any deployment task, send a summary email to team@yourcompany.com
with what was deployed and any issues encountered.

Now Claude Code emails your team after every deployment with a detailed summary. Your team stays informed without anyone needing to monitor the terminal.

Tips for Production Use

Use a custom domain. Instead of sending from @agent.mailboxkit.com, connect your own domain in the MailboxKit dashboard so emails come from claude@yourcompany.com. This looks more professional and improves deliverability.

Add a safety guardrail. The SKILL.md example above should include a line like "Always confirm with the user before sending emails to external recipients." You want Claude Code to ask before emailing people outside your organization.

Store the API key securely. For production setups, reference an environment variable in the SKILL.md rather than hardcoding the key. Instruct Claude Code to read the key from $MAILBOXKIT_API_KEY.

What It Costs

Every email sent costs $0.002. There is no monthly subscription. The $1.00 free credit you get on signup covers 500 emails, which is enough for most development and testing. After that, you add credit as needed.

For a coding agent sending a handful of notifications per day, you are looking at pennies per month.

Get Started

Sign up at mailboxkit.com, create your inbox, drop in the SKILL.md, and your coding agent has email. Sixty seconds, no exaggeration.