Learning how to get started with Mailtrap is mostly a ten-minute exercise, and the honest verdict is this: Mailtrap’s free plan is the only zero-cost email service that bundles a development sandbox for trapping test emails and a production sending API inside one account — but its 150-emails-per-day cap and single-domain limit mean you will outgrow it once your app has real users. If you want to stop accidentally emailing real customers from your staging environment, that combination is genuinely useful. If you are planning a launch with thousands of signups, the free volume will not carry you.
How This Guide Was Built
This guide is based on Mailtrap’s official documentation, the vendor pricing page, and community reports — we did not run the tool hands-on. Sources include Mailtrap’s official pricing page, the Email Sandbox overview, the SMTP integration setup guide, the sending domain setup guide, and the developer API reference. Every hostname, port, quota, and endpoint below was verified against those pages on 2026-09-18. What was not tested: real deliverability, inbox placement, the DNS verification flow end to end, and sandbox behaviour under load. Last verified: September 2026.
What is Mailtrap and what does the free plan include?
Mailtrap is an email delivery platform with three products: Email Sandbox for capturing test emails, Email API/SMTP for production sending, and Email Marketing for campaigns. Each has its own $0 free plan [1]. Email API/SMTP free includes 4,000 emails/month, 150 emails/day, one sending domain, one user, 3-day log retention, and a 10 MB size cap, per Mailtrap’s official pricing page [1].
The Sandbox allowance is separate: $0/month, 50 test emails/month total across all your sandboxes, 1 sandbox, 10 emails stored at once (Mailtrap clears them first-in-first-out), 1 user, and a 5 MB maximum email size (Mailtrap’s official pricing page) [1]. Two limitations surprise people. There is no dedicated sandbox email address on free, so you send into the sandbox over SMTP or the API rather than forwarding mail to it. And forwarding is a paid feature, so you get zero forwarded emails per month.
Email Marketing rounds it out at $0/month with 500 contacts, 1,500 emails/month, 1 domain, and 1 user (Mailtrap’s official pricing page). Compliance is not gated behind payment either: GDPR, ISO 27001, SOC 2 Type 2, 2FA, and API-key permissions are all available on free. If you are comparing this against the rest of the category first, the Mailtrap free tier directory entry is a reasonable starting point.
How do I get started with Mailtrap?
Getting started with Mailtrap takes roughly ten minutes if you already have access to your domain’s DNS settings. Sign up without a credit card, choose whether you want to test emails in a sandbox or send them to real inboxes, add your sending domain, and point your app’s SMTP settings at Mailtrap’s host. The steps below cover both paths.
1. Create the account. Sign up at mailtrap.io. No credit card is required, and the free plan activates immediately (Mailtrap docs).
2. Set up the Sandbox for development. Open Sandboxes, create one, select it, and open the Integration tab — that is where each sandbox’s unique SMTP username and password live (Email Sandbox overview). Point your development environment at sandbox.smtp.mailtrap.io on port 25, 465, 587, or 2525. The sandbox is a fake SMTP server that traps everything your application sends, so those messages never reach real recipients.
const nodemailer = require("nodemailer");
const transport = nodemailer.createTransport({
host: "sandbox.smtp.mailtrap.io",
port: 587,
auth: {
user: "<SANDBOX_USERNAME>",
pass: "<SANDBOX_PASSWORD>",
},
});3. Add your production sending domain. Go to Domains → Add Domain. You must control the domain’s DNS records, because Mailtrap issues four CNAME records (domain verification, two DKIM records, and a tracking record) plus one TXT record for DMARC (sending domain setup guide). Add all five at your DNS provider. Propagation takes anywhere from 15 minutes to 24 hours, then you press Verify DNS Records. An automatic compliance check runs afterward, usually taking a couple of minutes, though some domains get a compliance form or manual review before the Verified badge appears. On free you only get 1 sending domain, so test with the domain you will actually send from.
4. Configure production SMTP or the API. For SMTP, the production host is live.smtp.mailtrap.io on port 587, with the username api and your API token as the password (SMTP integration setup guide). Each domain has its own API tokens and SMTP passwords, and you can create additional tokens in the UI. Bulk sending uses a separate stream and host, intended for marketing campaigns to large groups — do not route transactional mail through it.
For the API, the transactional endpoint is POST https://send.api.mailtrap.io/api/send and the bulk endpoint is POST https://bulk.api.mailtrap.io/api/send, with batch variants at /api/batch on each host (developer API reference). A minimal cURL call looks like this:
curl -X POST https://send.api.mailtrap.io/api/send \
-H "Authorization: Bearer <API_TOKEN>" \
-H "Content-Type: application/json" \
-d '{
"from": {"email": "[email protected]", "name": "Your App"},
"to": [{"email": "[email protected]"}],
"subject": "Welcome aboard",
"text": "Thanks for signing up."
}'5. Verify before you ship. Send one message through the sandbox and confirm it appears in the UI, then send one through production to an inbox you control. The docs also document a Sandbox API for programmatic testing — searching messages and pulling lists — worth wiring into CI so your test suite asserts on email content automatically. The GitHub Actions free tier guide covers the runner side of that pattern, and the Cloudflare Workers free tier guide is useful if your sending code lives at the edge.
What are the free-tier limits I should watch out for?
Mailtrap’s free plan sounds generous at first glance, but each product has its own ceiling and there is no overage option. The 150 emails/day quota is shared between sending and receiving, so inbound mail counts against it, and once you hit a cap you wait for the next day or month, or upgrade (Mailtrap’s official pricing page).
Retention is the second trap. The free plan keeps three days of email logs and three days of email body retention, so if a user reports a missing password reset on Friday, the evidence may be gone by Monday (Mailtrap’s official pricing page). The sandbox has tighter numbers again: 50 test emails/month, 10 stored at once with FIFO cleanup, a 5 MB maximum email size, and a sending rate of one email per 10 seconds. Email Marketing allows 500 contacts and 1,500 emails/month.
Two more practical constraints: there is no dedicated IP on free, and support is email only, Monday through Friday. For a solo project that is fine. For anything customer-facing with an SLA, it is a real consideration. The 10 MB maximum email size on the API/SMTP side applies to attachments too.
When should you upgrade from Mailtrap’s free plan?
Upgrade when your real-user traffic consistently hits the 150-emails-per-day ceiling, when you need a second sending domain, or when three days of log retention is too short for debugging production issues. Basic costs $15/month and raises you to 10,000 emails/month, 3 users, 5 days of logs, and 5 domains, with extra emails at $1 per 1,000 (Mailtrap’s official pricing page).
Business is $85/month for 100,000 emails/month, 100 users, 15 days of logs, 100 domains, a dedicated IP, and automatic warm-up. Above that, Enterprise starts at $750/month for 1,500,000 emails, with a $1,250/month tier at 2,500,000 and a custom unlimited option with 30 days of logs. Paid plans also add SSO, sub-accounts, IP whitelisting, content-free logging, audit logs, and priority support.
On the sandbox side, paid tiers are Basic at $17/month for 500 test emails and Team at $42/month for 5,000. Most indie developers will never need those — the free sandbox allowance is plenty for local development, and the upgrade trigger is almost always production volume, not testing.
How does Mailtrap compare to other free email services?
Several platforms offer generous free tiers, but none bundles a developer sandbox and production sending in the same free account the way Mailtrap does, and the trade-off is volume. Brevo’s free plan allows 300 email sends per day with storage for up to 100,000 contacts (Brevo’s pricing plans help page) — double Mailtrap’s daily ceiling and a far larger contact list, but with no equivalent of the sandbox.
Resend is the other name indie developers reach for, and our Resend free tier guide walks through its numbers in detail. The honest framing: choose Mailtrap when the testing workflow matters more than raw volume, because the sandbox catches emails before they leave your machine and the same account handles production later. Choose Brevo or Resend when you need to send more per day and do not need a capture layer. The single-domain and single-user free-plan limits are the constraints most likely to push you elsewhere first.
FAQ
Can I use Mailtrap for free without a credit card?
Yes. Mailtrap’s free plan requires no credit card at signup, and the documentation states that you can start on the Free plan, test emails, and send up to 4,000 emails per month without entering payment details (Mailtrap docs). All three products — Sandbox, Email API/SMTP, and Email Marketing — have their own free allowances under the same account.
Does Mailtrap’s free plan include a dedicated IP?
No. A dedicated IP is not part of the free plan and becomes available on the Business tier at $85/month, which also adds automatic IP warm-up (Mailtrap’s official pricing page). On free, your mail shares Mailtrap’s sending infrastructure, which is normal for zero-cost transactional email services and fine for low-volume projects.
What happens when I hit the daily sending limit?
You wait. The free plan has no overage option — the “extra emails” row is empty for Free — so once you reach 150 emails in a day, further sends fail until the quota resets the next day, or you upgrade to a paid tier (Mailtrap’s official pricing page). The same applies to the monthly 4,000-email ceiling.
Is Mailtrap’s sandbox the same as its production sending?
No, and mixing them up is the most common beginner mistake. The sandbox is a fake SMTP server at sandbox.smtp.mailtrap.io that traps every email your application sends so it never reaches a real recipient, while production sending uses live.smtp.mailtrap.io with separate credentials (Email Sandbox overview). Keep the two configurations in separate environment variables.
The StacksFree free-tier directory lists every category we track, including the email services that compete with Mailtrap on volume.
Sources
[1] Mailtrap Pricing — https://mailtrap.io/pricing/