​
Simulate message events

Test your email integration safely—trigger predictable delivery events using Lettermint’s built-in test addresses. No risk to real users, no production data required.

Why use test addresses?

Sending test emails to real mailboxes (including your own) can harm your sender reputation. Repeated bounces, spam complaints, or test content flagged as suspicious may cause mailbox providers to throttle or block your domain. Lettermint’s test addresses let you simulate every scenario without risking your deliverability or reputation.

​
1. Send a Test Email

Simulate real-world delivery scenarios by sending to Lettermint’s special test addresses. Each address triggers a specific event, letting you verify your handling of bounces, complaints, and successful deliveries.

​
Example: Simulate a Soft Bounce

curl -X POST https://api.lettermint.co/v1/send \
  -H "x-lettermint-token: $TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
        "from": "you@acme.io",
        "to": ["softbounce@testing.lettermint.co"],
        "subject": "Test soft bounce",
        "text": "This should soft bounce."
      }'
# → 202 Accepted
#   Later: status = soft_bounced

This sends a test email that always results in a soft bounce (“mailbox full”). Swap the to address to simulate other outcomes.

​
2. Test Addresses and Their Behaviors

Use these addresses to trigger specific events:

AddressSimulated Event
ok@testing.lettermint.coDelivered
softbounce@testing.lettermint.coSoft bounce (“mailbox full”)
hardbounce@testing.lettermint.coHard bounce (“user does not exist”)
spamcomplaint@testing.lettermint.coDelivered → Spam complaint event
dsn@testing.lettermint.coOut-of-band DSN bounce

These test addresses are only reachable from Lettermint’s system. They cannot be used for real-world delivery or external testing.

​
Troubleshooting

Test address returns error

  • Ensure you’re using a valid Lettermint API token.
  • Confirm the to address matches one of the documented test addresses.

No event received

  • Test events may take a few seconds to process.

​
Next Steps

  • Integrate Lettermint webhooks to receive delivery and bounce events.
  • Test with your real application logic.
  • Explore advanced features: Lettermint API Reference