smtp.dev

Guides

AI Agents

Give automation a disposable sandbox address and API key so it can read OTP codes and confirmation links without touching a real inbox.

Per-run addresses

Use a catch-all account or plus-addressing to generate addresses like agent+run-42@dev.example.test. The original recipient stays in the parsed message fields, which makes each agent run traceable and searchable.

API-only access

Store the API token as a secret, pass it as X-API-KEY, and poll the mailbox message list for the expected subject or recipient tag. Keep the sandbox restricted to development data and expire messages after the run.

curl -H "X-API-KEY: $SMTPDEV_API_KEY" \
  "https://stmp.ink/api/accounts/1/mailboxes/1/messages?q=agent%2Brun-42"