# Send Log data extensions and send logging

*Marketing Cloud Engagement Developer Study Guide · Data Management · Last updated November 3, 2026 · https://www.certifyforce.com/study-guide/marketing-cloud-engagement-developer/data-management/send-log-data-extensions-and-send-logging*

How a send log captures send-time values: creating it from the SendLog template, how fields get filled, which send types log by default, retention and field-size practices, joining the log to data views, error codes and duplicate records.

- Certification: Salesforce Marketing Cloud Engagement Developer
- Exam section: Data Management
- Study guide: https://www.certifyforce.com/study-guide/marketing-cloud-engagement-developer

**Official exam objective:**

> Given a scenario, apply best practices for send logs.

## What the exam expects

- Create an email send log from the SendLog template with the right sendable and retention settings, within the one-per-account limit.
- Populate custom send log fields from sendable data, AMPscript variables and personalization strings.
- Know which send types log by default, which can be switched off, and which need Support.
- Apply the field, retention and concurrency best practices, and restart running sends so they log to a new send log.
- Join the send log to data views, count error codes and handle duplicate records in reports.
- Key terms: **send log** (a data extension recording send-time data for each message); **SendLog template** (the data extension template that creates it); **send-time data** (values as they were when the message was built); **SubID** (the send log's subscriber ID field); **ErrorCode** (the send log field that records send errors).

## Key facts

| Fact | Detail | Source |
|---|---|---|
| Limit | One email and one SMS send log template and data extension per account | [Send Logging in Email Studio](https://help.salesforce.com/s/articleView?id=mktg.mc_es_send_logging.htm&language=en_US&type=5) |
| Is Sendable | Left unchecked | [Create an Email Send Log](https://help.salesforce.com/s/articleView?id=mktg.mc_cab_create_an_email_send_logging_data_extension.htm&type=5&language=en_US) |
| Default fields | JobID, ListID, BatchID, SubID, TriggeredSendID, ErrorCode | [Create an Email Send Log](https://help.salesforce.com/s/articleView?id=mktg.mc_cab_create_an_email_send_logging_data_extension.htm&type=5&language=en_US) |
| Retention | 10 days (best practices); 30 days or shorter (storage guidance) | [Send Logging Best Practices](https://help.salesforce.com/s/articleView?id=mktg.mc_es_send_logging_best_practices.htm&language=en_US&type=5), [Data Extension Storage Usage](https://help.salesforce.com/s/articleView?id=mktg.mc_as_data_extension_storage.htm&type=5&language=en_US) |
| Custom fields | 10 or fewer | [Send Logging Best Practices](https://help.salesforce.com/s/articleView?id=mktg.mc_es_send_logging_best_practices.htm&language=en_US&type=5) |
| Dates | UTC-6 | [Send Logging Best Practices](https://help.salesforce.com/s/articleView?id=mktg.mc_es_send_logging_best_practices.htm&language=en_US&type=5) |
| Not logged by default | Test, transactional and HTS sends | [Send Logging Article](https://help.salesforce.com/s/articleView?id=000386631&language=en_US&type=1) |
| Error codes | 19 Missing Required Fields; 24 List Detective Exclusion | [Send Logging Article](https://help.salesforce.com/s/articleView?id=000386631&language=en_US&type=1) |

## Check yourself

- Which messages does a MobilePush send log include?
- Why can adding custom fields be risky for a send log?
- When does a send actually record its data to the send log?
- Why does Help recommend a retention policy when you create the log?

## Sources

- [Engagement - Send Logging Marketing Cloud Engagement Email Sends](https://help.salesforce.com/s/articleView?id=000386631&language=en_US&type=1)
- [Send Logging in Email Studio](https://help.salesforce.com/s/articleView?id=mktg.mc_es_send_logging.htm&language=en_US&type=5)
- [Send Logging Best Practices and Tips](https://help.salesforce.com/s/articleView?id=mktg.mc_es_send_logging_best_practices.htm&language=en_US&type=5)
- [Create an Email Send Logging Data Extension](https://help.salesforce.com/s/articleView?id=mktg.mc_cab_create_an_email_send_logging_data_extension.htm&type=5&language=en_US)
- [Data Extension Storage Usage](https://help.salesforce.com/s/articleView?id=mktg.mc_as_data_extension_storage.htm&type=5&language=en_US)
- [Transactional Messaging API](https://developer.salesforce.com/docs/marketing/marketing-cloud/guide/transactional-messaging-api.html)

## About the full unit

The "Core concepts", "Exam traps" and "Worked scenario" sections of this unit, its 11 linked practice questions, and unlimited timed mock exams are included with the Marketing Cloud Engagement Developer pack (USD $19): https://www.certifyforce.com/practice-exams