Email Testing for Developers

Test emails like you debug code. SMTP in, IMAP/API out. Inspect headers, MIME and raw source. Nothing leaves the sandbox.

SMTP, IMAP, POP3

Your existing mail clients work out of the box. No vendor SDK, no lock-in.
  • Quick setup
    Point an MX record and the domain receives real email from any service. No setup wizard, no 50-page guide.
  • REST API
    Accounts, messages, domains, tokens. API-first.
  • Message inspection
    Headers, MIME tree, raw RFC 5322. See exactly what arrived.
SMTP, IMAP and POP3 protocol support

After delivery

Check what arrived in the UI or wire it into CI.
  • Delivery checks
    HTML preview, text, headers, raw source. Plus SPF/DKIM/DMARC results via API.
  • CI-ready
    Standard SMTP - any CI that sends email works. GitHub Actions, Jenkins, GitLab CI, whatever you use.
  • Deliverability audit
    Sender config, HTML structure, links, and the content patterns spam filters flag. Grouped by severity.
Email message preview with headers, HTML and raw source
Quickstart

Send, read, assert

Your app sends over SMTP. Your test reads the result over the API. The whole loop fits on one screen.
# create an inbox
curl -X POST https://api.smtp.dev/accounts \
  -H "X-API-KEY: $SMTP_DEV_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"address": "qa@example.com", "password": "use-a-secret"}'

# your app sends to it, then read what arrived
curl "https://api.smtp.dev/accounts/$ACCOUNT/mailboxes/$INBOX/messages" \
  -H "X-API-KEY: $SMTP_DEV_API_KEY"

What you can test

Each card links to a guide.
CI assertions
Send from the test suite, poll the API, assert on subject and body.
E2E flows
The Playwright test clicks the real reset link from the real email.
SPF, DKIM, DMARC
Authentication verdicts from staging before you touch production DNS.
QA signups
A catch-all account hands every test run a fresh address on your domain.
Client previews
The same message in Thunderbird and Apple Mail, over plain IMAP.
AI agents
Agents read OTP codes and confirmation links over the API. In dev, not in your inbox.

Features

Custom Domains
Bring your own domains and subdomains. One MX record each.
Disposable Accounts
Create an address per test run over the API. Delete it after.
Unlimited Messages
On every plan - no daily caps, no metering.
Sandboxed
Receives real email from any service. Sends only within the sandbox.
SPF, DKIM, DMARC
Checked on every inbound message. Results in the UI and the API.
Retention Timers
Messages kept for your plan's window, up to 90 days. Per-message expiry for shorter.
REST API
Domains, accounts, mailboxes, messages, tokens. OpenAPI spec included.
Real-time Updates
New messages pushed via SSE. No polling.
Catch-All & Aliasing
Wildcard accounts and plus-sign addressing. Capture everything or route by tag.

Start testing

Sign up, add a domain, receive your first test email.