What is the difference between a bounce and a dropped event in SendGrid?

A bounce means the receiving server accepted then rejected the message, or rejected it during the SMTP conversation — the email reached a mail server. A dropped event means SendGrid never attempted delivery, usually because the address is on a suppression list (previous bounce, spam report, unsubscribe, or invalid).

What does a deferred event mean?

A deferred event means the receiving server temporarily rejected the message (a 4xx SMTP response) and SendGrid will retry. It is not a failure — repeated deferrals over the retry window eventually turn into a bounce if the server never accepts the message.

How are open and click events tracked?

Opens are tracked with a 1x1 tracking pixel inserted into HTML emails, so an open event fires when images load. Clicks are tracked by rewriting links to redirect through SendGrid, which records the original url field before forwarding. Both require the corresponding tracking setting to be enabled.

Which events should suppress future sends?

Bounce (hard), dropped, spamreport, and unsubscribe events add the address to a suppression list and you should stop mailing it. Soft bounces and deferred events are transient. Group unsubscribe events (group_unsubscribe) only suppress a specific unsubscribe group, not all mail.

Is anything I search uploaded?

No. The full event index and the search run entirely in your browser. Nothing you type is sent to any server.

SendGrid / Twilio Email Event Types

This is a searchable reference for SendGrid (Twilio) Event Webhook event types — every event value SendGrid POSTs to your endpoint, grouped into delivery, engagement, and account categories. Each entry lists the key JSON fields the event carries and what it means, so you can build a reliable handler that updates send status, suppresses bad addresses, and records engagement.

How it works

SendGrid POSTs an array of JSON objects to your configured webhook URL. Every object shares common fields and adds event-specific ones:

{
  "email": "[email protected]",
  "timestamp": 1717689600,
  "event": "bounce",
  "sg_event_id": "abc123",
  "sg_message_id": "msg.0001",
  "reason": "550 5.1.1 user unknown",
  "type": "bounce"
}

Events fall into three categories. Delivery events (processed, deferred, delivered, bounce, dropped) track the lifecycle from acceptance into SendGrid through to the receiving server. Engagement events (open, click, spamreport, unsubscribe, group_unsubscribe, group_resubscribe) track what the recipient did. The bounce event’s type field (bounce vs blocked) and the reason field tell you whether the failure was hard (permanent) or soft (temporary).

Tips and example

Idempotency matters: SendGrid may deliver the same event more than once, so dedupe on sg_event_id before applying state changes. Drive suppression off permanent-failure and complaint events:

processed  → queued, handed to the receiving MTA
delivered  → accepted by the recipient server (success)
deferred   → temporary 4xx, will retry (not a failure)
bounce     → rejected; check type=bounce (hard) vs blocked (soft)
dropped    → never sent (on a suppression list)
spamreport → recipient hit "mark as spam" — suppress immediately

Treat open and click as engagement signals only — they can be inflated by image proxies and link scanners, so never gate critical logic on a single open event. Everything runs in your browser; nothing is uploaded.

SendGrid / Twilio Email Event Types

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How it works

Tips and example