Data is both a differentiating asset for companies and an existential liability. Slack, as the operating system for modern work, contains data not just from Slack but from all the various apps and services that connect to Slack. This amounts to a ton of data, some of which is sensitive.

By default, Slack stores messages and files for the lifetime of your Slack Workspace. As long as a company uses Slack, the data in Slack will be stored. The only caveat to this default data retention is that data from deleted channels is deleted when the channel is deleted.

There are reasons to retain data indefinitely. These reasons include legal reasons such as e-discovery and investigations as well as company reasons such as using Slack data as a knowledge base.

But, in some instances, data should not be stored indefinitely. Two examples highlight use cases where data should not be retained forever. First, PII that has been requested for deletion under a regulatory framework such as GDPR or CCPA. This is a hard problem to solve since you can delete the user data from certain apps but, if those apps are integrated with Slack, the PII might still be in Slack. The Second use cases pertains to healthcare data. The minimal amount of PHI under HIPAA should be shared as required for the specific need. After that need has been met and assuming no need to retain the PHI for medical legal reasons, the PHI can be deleted.

Slack provides admins the ability to configure data retention policies for both messages and files. These configurations are in the Workspace Settings in the Slack admin channel. The options are below.

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The following three options are available in Slack for data retention across all channels and messages.

1. Keep everything. This is the default setting.
2. Keep all messages, but don't track revisions. Slack will not delete messages but will not track edits or deletions.
3. Delete messages and their revisions after... Slack deletes messages after a certain, defined time frame.

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The above settings are Slack-wide. Workspace owners can allow admins and members to set their own data retention policies.

1. Admin overrides allow admins to set data retention for channels. This is only an option for Business+ and Enterprise Grid users.
2. Member overrides allow Slack users to set data retention for DMs and private channels.

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If messages are deleted from Slack, they are deleted permanently. There is no going back. 

In addition to the above data retention options for Slack messages, data retention settings can be adjusted for files shared in Slack. The following options exist for Slack file retention.

1. Keep all files. This is the default setting.
2. Keep all files, only for a set number of days. Files are deleted after a certain, admin-defined, number of days.
3. Keep all files, including deleted files. Slack will keep all files. Any deleted files will be available for export via API.
4. Keep all files, including deleted files, for a set number of days. Files are deleted after a certain, admin-defined, number of days. Any deleted files will be available for export via API.

Importantly, data retention policies should align with Slack data retention settings.  Ideally, a company has a data retention policy in place. If not, one should be created. This is a first step in determining how to configure Slack data retention rules.