---
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"@id": https://www.twilio.com/docs/sendgrid/glossary/reserved-fields#article
headline: Reserved fields
description: "*Configuration*. Predefined and protected attributes provided for email contacts."
url: https://www.twilio.com/docs/sendgrid/glossary/reserved-fields
inLanguage: en
dateModified: 2026-07-23T16:57:51.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# Reserved fields

*Configuration*. Predefined and protected attributes provided for email contacts. These are another type of [custom field][custom fields].

In Marketing Campaigns, they include fields such as `email`, `first_name`, and `last_name`.

To learn more, see [Reserved fields in custom fields][reserved-fields].

[reserved-fields]: /docs/sendgrid/ui/managing-contacts/custom-fields#reserved-fields

[custom fields]: /docs/sendgrid/glossary/custom-fields