Replit

In this guide, you'll set up production email sending in a Replit project using the Mailtrap Email API with official SDKs (Node.js or Python), and learn how to create or update contacts in Mailtrap directly from your app.

You'll:

• Send emails from your verified domain via the Mailtrap Email API

• Store contacts for campaigns and automations, with optional custom fields and list membership

This tutorial uses the Replit Agent product.

Prerequisites

• Verified sending domain in Mailtrap (required for production) — Setup guide

• Admin API token with access to your verified domain and Contacts

• Account ID (needed for Contacts) — find it here

• Custom fields created in Mailtrap if you want to store extra structured data — create here

• (Optional) List ID if you want to assign contacts to a list

• Replit account and project (Node.js or Python)

Ready-made prompts (for Replit Agent)

Sending only

Prompt
Create a Node.js app that uses the Mailtrap SDK to send a production email via the Email API using a verified domain. Store the API token and from address in environment variables.

Replit Agent sending prompt result

To complete the project, Replit asks you to provide Mailtrap API token and the FROM_ADDRESS. Make sure to add and verify a domain first.

Contacts management only

Prompt
Write a Node.js script that uses the Mailtrap SDK to create or update a contact in Mailtrap. Include email, name, and custom fields. Store Account ID, API token, and optional List ID in environment variables.

Replit Agent contacts prompt result

To complete the project, Replit asks you to provide MAILTRAP_ACCOUNT_ID token and the MAILTRAP_LIST_ID.

Step-by-step setup

1

Set up Mailtrap

1. Verify your sending domain in Mailtrap.

2. Create an admin API token and keep it secure.

3. Note your FROM_ADDRESS (must use the verified domain).

2

Create/open your Replit project

With Replit Agent - Use one of the prompts above. Replit does it all, you just need to add the credentials.

Manual setup:

Install SDKs:

Node.js

npm install mailtrap

Python

Add secrets in Replit (use the Secrets panel):

MAILTRAP_API_TOKEN = <your_admin_api_token>

3

Send a production email

Node.js

import { MailtrapClient } from "mailtrap";

const client = new MailtrapClient({ token: process.env.MAILTRAP_API_TOKEN });

await client.send({
  from: { email: "[email protected]", name: "Your App" },
  to: [{ email: "[email protected]", name: "Recipient" }],
  subject: "Welcome to Our App",
  text: "Hello from Mailtrap + Replit!"
});

console.log("Production email sent.");

Python

4

Run and verify

1. Click Run in Replit. (Note: Most of the time, the AI IDE does it for you.)

2. Check the recipient's inbox.

Troubleshooting

• FROM_ADDRESS rejected - Use a verified domain.

• 401/403 errors - Ensure API token is admin-level.

Next steps

• Add Mailtrap Templates for branded messages.

• Implement Contacts Management to store new subscribers in Mailtrap.