# Bounce categories, spam complaints and deliverability

*Marketing Cloud Engagement Foundations Study Guide · Reporting and Analytics · Last updated November 3, 2026 · https://www.certifyforce.com/study-guide/marketing-cloud-engagement-foundations/reporting-and-analytics/bounce-categories-spam-complaints-and-deliverability*

How to read bad send results: hard, soft, block and technical bounces and what each calls for, how bounces move a subscriber from Bounced to Undeliverable, what to check after block bounces, and why spam complaints unsubscribe people and hurt reputation.

- Certification: Salesforce Marketing Cloud Engagement Foundations
- Exam section: Reporting and Analytics
- Study guide: https://www.certifyforce.com/study-guide/marketing-cloud-engagement-foundations

**Official exam objective:**

> Interpret undesired send results and possible deliverability consequences.

## What the exam expects

- Classify a bounce reason as hard, soft, block or technical, and say what the marketer should do next.
- Tell a block bounce apart from a hard bounce, and list the checks Salesforce recommends after block bounces.
- Explain how repeated bounces change a subscriber's status.
- Predict what a spam complaint does to the subscriber and to the sender's reputation, and pick remedies for negative engagement.
- Key terms: **bounce** (a message the ISP sends back explaining why it couldn't deliver the email); **hard bounce** (a permanent failure such as an unknown user or domain); **soft bounce** (a temporary failure such as a full mailbox); **block bounce** (mail refused for authentication, volume or reputation reasons); **technical bounce** (a rejection for technical errors such as formatting or connection problems); **Undeliverable** (the status after repeated bounces, shown as Held on some pages).

## Key facts

| Fact | Detail | Source |
|---|---|---|
| Hard bounce | Permanent: user or domain doesn't exist | [Bounce Categories and Reasons](https://help.salesforce.com/s/articleView?id=000387252&type=1) |
| Mailbox Full | Soft bounce; may mean an abandoned mailbox | [Bounce Categories and Reasons](https://help.salesforce.com/s/articleView?id=000387252&type=1) |
| Data Format Error | Technical bounce; often more than 999 characters on one line | [Bounce Categories and Reasons](https://help.salesforce.com/s/articleView?id=000387252&type=1) |
| Soft bounce count | All retries of one message count as one soft bounce; the third sets Held (Undeliverable) | [Bounce Mail Management](https://help.salesforce.com/s/articleView?id=mktg.mc_es_bounce_mail_management.htm&type=5&language=en_US) |
| Undeliverable | Third bouncing campaign, more than 15 days after the first bounce; one hard bounce from a trusted domain | [Bounce Mail Management](https://help.salesforce.com/s/articleView?id=mktg.mc_es_bounce_mail_management.htm&type=5&language=en_US) |
| Block bounce checks | Volume trend, SPF and DKIM, hard bounces, content size | [How to Handle Block Bounces](https://help.salesforce.com/s/articleView?id=000395280&type=1) |
| Spam complaint | Subscriber unsubscribed automatically | [Identify Spam Complainers](https://help.salesforce.com/s/articleView?id=000383511&type=1) |
| Metric review cadence | Every three to six months | [Addressing Delivery and Reputation Issues](https://help.salesforce.com/s/articleView?id=mktg.mc_es_email_deliverability_best_practices.htm&type=5&language=en_US) |

## Check yourself

- Why can't a sender usually tell whether a block bounce is temporary or permanent?
- When should a sender ask the ISP directly to remove a block?
- How is a bounce with no identifying error code treated?
- What does Help suggest for data capture that keeps producing User Unknown bounces?

## Sources

- [Bounce categories and reasons for Marketing Cloud Engagement email sends](https://help.salesforce.com/s/articleView?id=000387252&type=1)
- [How to Handle Block Bounce Occurrences](https://help.salesforce.com/s/articleView?id=000395280&type=1)
- [Bounce Mail Management in Email Studio](https://help.salesforce.com/s/articleView?id=mktg.mc_es_bounce_mail_management.htm&type=5&language=en_US)
- [Identify subscribers marking email as Spam in Marketing Cloud](https://help.salesforce.com/s/articleView?id=000383511&type=1)
- [Addressing Delivery and Reputation Issues](https://help.salesforce.com/s/articleView?id=mktg.mc_es_email_deliverability_best_practices.htm&type=5&language=en_US)

## About the full unit

The "Core concepts", "Exam traps" and "Worked scenario" sections of this unit, its 7 linked practice questions, and unlimited timed mock exams are included with the Marketing Cloud Engagement Foundations pack (USD $19): https://www.certifyforce.com/practice-exams