Test the edge cases.
Before your users find them.

Eight delivery and failure scenarios. Exercise your email pipeline and webhook handlers without sending to real recipients.

Start for free Read the quickstart

Create a test key

Test keys run the full pipeline and never deliver to real recipients.

Choose an outcome

Test delivery, bounce, mailbox full, blocked, delayed, complaint, suppression, or a specific SMTP bounce code.

Check your handling

Inspect the event shape and confirm your application updates the right records.

const response = await fetch(
  process.env.ZAPSMTP_API_URL, {
  method: 'POST',
  headers: {
    'Authorization': 'Bearer zap_your_api_key',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    from: 'hello@yourdomain.com',
    to: ['delivered@simulator.zapsmtp.com'],
    subject: 'You’re all set.',
    html: '<p>Your next big thing starts here.</p>'
  })
});

Set ZAPSMTP_API_URL to your account’s send endpoint.

Try a delivery scenario.Local simulation. No real email is sent.

Eight scenarios, one workflow

Delivered, bounced, mailbox full, blocked, delayed, complained, suppressed, and bounce with a specific SMTP code.

Bounce details your handler understands

Inspect Permanent and Transient bounce types, with a subtype for more precise handling.

Use the full pipeline safely

Keys starting with zap_test_ run the full pipeline without delivering email to real people.

Try the event flow here

The interactive example on this website is a local simulation. It does not call the sending API or display live product events.

Plan limits

API and SMTP are included in every plan. Free includes 3,000 emails per month, one domain, and three days of logs. Pro includes ten domains and 30 days of logs; Scale includes unlimited domains and 90 days of logs.

Compare plans

Good to know

Verify your domain before production sending. Keep API keys and SMTP passwords on your backend. Delivery depends on content, reputation, authentication, and the receiving provider; an accepted request does not guarantee inbox placement.

Send your first email.

Your next email starts with a few lines of code.

Start building 3,000 emails / month free

Test the edge cases.Before your users find them.