SMTPeter allows you to set up Webhooks, previously named Feedback Loops. These Webhooks can be used to receive realtime event notifications. Every time when something happens on the SMTPeter servers (like an incoming bounce, a failed delivery or when someone clicks on a link), SMTPeter makes a call to your server to notify you about this event.

The webhook is sent over the HTTP or HTTPS protocol using the HTTP POST mechanism. When you set up a webhook, you register a web address and specify the type of events that you are interested in. Once your URL has been validated, SMTPeter starts making calls to it.

Watch out!

Before you set up a webhook, please do make sure that your server is capable of handling the load. Especially the webhook that is called when someone opens a mail receives huge numbers of calls.

If you're not sure whether your server can handle the load, or when you do not need realtime feedback, you better use the REST API to periodically download the latest log files. The REST API gives you access to exactly the same data as the webhooks, but you stay in control and you decide when to fetch the data.


To protect your endpoint from abuse and false information injection, SMTPeter signs all requests to your endpoint.

Type of events

The following webhooks can be used: