---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/sendgrid/glossary/undelivered-email#article
headline: Undelivered Email
description: "*Email Deliverability*. A category of reasons why an email message wasn't delivered to a recipient's inbox."
url: https://www.twilio.com/docs/sendgrid/glossary/undelivered-email
inLanguage: en
dateModified: 2026-07-23T16:57:51.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# Undelivered Email

*Email Deliverability*. A category of reasons why an email message wasn't delivered to a recipient's inbox. These reasons cover issues with the recipient's email address or the email message content.

When an email send attempt fails, one of the following happens to your email message:

* [Bounced][]. Recipient email server rejects an email message sent to this recipient's email address.
* Marked as [Spam][]. The recipient marked this email message as spam.
* [Dropped][]. The recipient had been added to a [suppression list][].
* Set as [Invalid][]. The recipient email address doesn't exist.

[Bounced]: /docs/sendgrid/glossary/bounces

[spam]: /docs/sendgrid/glossary/spam

[Dropped]: /docs/sendgrid/glossary/drops

[Invalid]: /docs/sendgrid/glossary/invalid-email

[suppression list]: /docs/sendgrid/ui/sending-email/index-suppressions