Can I see how a message was sent (API or SMTP)?

Postmark’s message activity logs don’t include details about the specific API or SMTP token used to send a message. This means you won’t be able to tell directly from the Activity page whether a message was sent via the API or SMTP.

If you’re trying to confirm how a message was sent, here are a few ways to check:

• API sends: Messages sent via the API will appear in your server’s Activity just like SMTP sends, but you can confirm by reviewing your application’s code or integration logs to see if it uses Postmark’s Email API.

• SMTP sends: If you’ve configured an app, website, or device with your SMTP credentials, messages from that system will have been sent via SMTP.

For security reasons, Postmark does not store or display API or SMTP tokens in message logs.

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🔍 Recommended next steps

If you need to confirm how a message was sent or troubleshoot delivery issues:

1. Check your application settings:

   • Look for “SMTP” or “API” in your app or plugin’s email configuration.

   • If you see a Server Token being used, that indicates API sending.

   • If you see username and password credentials (e.g., Server Token as the username), that indicates SMTP sending.

2. Review recent API or SMTP activity:

   • Check your app’s logs or error reports to see how messages were transmitted.

   • If you’re using SMTP, ensure your system is using the correct SMTP server and port from our SMTP setup guide.

3. Still not sure?

   • If it’s urgent or unclear, reach out to our Support team. We can verify with our technical team whether recent connections came through API or SMTP.