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When it triggers

This event fires when the recipient reports the email as spam through their email client. This generates a complaint feedback loop report.
Complaint rates are closely monitored by email providers. High complaint rates can lead to domain-wide deliverability issues. The recipient is automatically added to the suppression list.

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Payload

{
  "type": "email.complained",
  "data": {
    "email_id": "em_abc123",
    "from": "hello@yourdomain.com",
    "to": "user@example.com",
    "subject": "Welcome to SendKit",
    "created_at": "2026-03-02T12:10:00+00:00"
  },
  "created_at": "2026-03-02T12:10:00+00:00"
}

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Payload fields

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email_id
string
Unique identifier of the email.
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from
string
Sender email address.
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to
string
Recipient email address.
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subject
string
Email subject line.
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created_at
string
ISO 8601 timestamp of when the email was created.