As emails are sent and recipients interact with them, events are triggered within SendGrid. All SendGrid customers can enable the Event Webhook to receive notifications for the nine types of email events described below.

Some are informational and can be used to create instant dashboards. Others you may want to save to query later. And there are some events you may want to react to immediately. Your project may not require listening for all nine, but each is useful in its own way. For a deeper dive on SendGrid’s event webhook, download our Event Webhook Guide.


This event fires when SendGrid receives an individual message and prepares it to be delivered. Think of this as the top of the funnel–unless it is dropped (see below), each message you push to SendGrid will create a processed event.


There are a number of reasons your email will not even be sent to a recipient for delivery. This event informs your system when an email has been dropped. Further, it provides a reason for the drop, such as if we’ve found spam content (if spam checker app is enabled) or we see the recipient has unsubscribed previously.


When an email cannot immediately be delivered, but it hasn’t been completely rejected, the deferred event fires. Sometimes called a soft bounce, SendGrid will continue to try for 72 hours to deliver a deferred message.


If a server cannot or will not deliver a message, SendGrid fires a bounce event. Bounces often are caused by outdated or incorrectly entered email addresses. Many times you won’t know a bounced email address until it bounces. This event can help you ensure it doesn’t bounce again by removing it from your lists.


When an email has been accepted at the receiving server, the delivered event fires. This event does not guarantee that the email was placed in the recipient’s inbox. In fact, a delivered email is only the beginning of an opaque process. The remaining four events begin to give us hints about whether anyone will ever see this delivered email.


An opened email is the first step toward the action you want your recipient to take. This event fires every time the email is viewed with images turned on. Like all email service providers, SendGrid uses a transparent image beacon to track opened messages. This beacon is currently the only way a sender can tell if an email has been opened. (To learn how image opens are affected by Google’s new image caching, read our blog post on the topic here.)


The pinnacle of email engagement is the click. Your call to action, whether it is to confirm a newly registered account or to view a recommended product, asks the recipient to click a link. SendGrid tracks that interaction and fires a click event.

Spam Report

Most internet service providers provide a feedback loop, sending specific spam complaints to the email service providers. When SendGrid receives a notice, we fire a spam event, so that you can react appropriately–or at the very least, never send another email to that address.


One of the most important events fires when a recipient unsubscribes from your mailings. Reacting immediately to an unsubscribe by removing the email from your lists can pay long term dividends in fewer spam reports and a higher engagement rate.

These nine events are the core of the Event Webhook. To dive even deeper into how to use the webhook, some case studies of successful integrations and a technical overview, download the Event Webhook Guide.

Adam DuVander speaks fluent "developer" while serving as Developer Communications Director. He helps SendGrid connect to coders of all stripes. Previously Adam wrote for Wired, Webmonkey and edited ProgrammableWeb, the leading resource for APIs.