---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/sendgrid/glossary/unknown-user#article
headline: Unknown User
description: "*Email Deliverability*. A bounce reason indicating that the recipient email address doesn't exist on the recipient email server."
url: https://www.twilio.com/docs/sendgrid/glossary/unknown-user
inLanguage: en
dateModified: 2026-07-23T16:57:51.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# Unknown User

*Email Deliverability*. A bounce reason indicating that the recipient email address doesn't exist on the recipient email server.

This error displays as `Bounced - Unknown User`. When it occurs, remove the recipient email address from your contact list.

## Additional resources

* [Delivery Metrics](/docs/sendgrid/ui/analytics-and-reporting/stats-overview/)
* [Bounces](/docs/sendgrid/glossary/bounces/)
* [Subscriber List Management](/docs/sendgrid/glossary/subscriber-list-management/)