Slack Archiving: How It Works and What You Need to Know

Platforms like Slack are integral to fostering effective collaboration among distributed teams, but they generate vast amounts of data that must be managed and stored or purged appropriately. Slack’s native archiving feature provides a convenient way for workspace administrators to streamline their Slack environment, but is it a reliable retention tool? This post explores the uses and benefits of Slack archiving for retention and how to use it effectively to avoid data loss in Slack.

What is Slack archiving?

Slack archiving is a feature designed to help teams manage their communication history by hiding inactive public and private channels from the Slack workspace. This simplifies the Slack environment, reducing the number of active channels to more manageable volume while preserving disused channels, messages, DMs, and files and while keeping them accessible for future reference. Archiving is often a simple and effective way of maintaining a searchable repository of Slack data.

Who can archive Slack data?

Slack allows all workspace members to be able to archive channels by default, without having to be a channel member. Equally, any single user can unarchive a channel and restore it to the live Slack environment. Workspace owners and admins can use additional options to restrict archiving capabilities if required, and only an owner or admin can delete a Slack channel, whether it’s active or archived.

How to archive a Slack channel

By default, any user can archive any Slack private or public channel except #general, which cannot be archived. To archive a Slack channel, follow these steps:

• Click on the channel name
• Choose the Settings tab in the pop-up window
• Scroll down to Archive channel for everyone
• Any users within that channel will be notified that you archived it

Once a channel is archived, no new messages can be sent in it, and apps installed in the channel will be disabled. Chat history and files will still be accessible and searchable. The ability to archive a channel may be restricted by workspace owners or admins. Archiving a channel is reversible; deleting a channel permanently erases the contents.

Does Slack delete archived channels?

Archived Slack channels are retained according to the settings of the workspace, although depending on your Slack membership level, some of the content within the channel may not be immediately accessible. Messages are only permanently removed when workspace admins delete Slack channels or when purged by retention policies. Administrators have the option of deleting both live and archived channels at any time.

Admins can also amend how long an archived channel’s data is kept by adjusting the workspace retention policies. Customized retention periods override default settings and apply to all channels, including archived ones.

Slack archiving vs. Slack back-up—what's the difference?

• Slack Archiving: Hides data for space management and future reference but doesn't offer true data security.
• Slack Back-up: Creates a separate, secure copy of data for disaster recovery and legal compliance.

Slack archiving

Slack’s archiving feature does two things:

1. Removes the channel from the active list in the Slack sidebar.
2. Prevents users from adding or deleting messages in archived channels.

Pros of Slack archiving:

• Users retain some control over content within archived channels. Messages cannot be added or deleted, but they can be forwarded, unarchived and edited, and re-archived.
• Slack retains data indefinitely by default, so archiving a Slack channel also preserves it indefinitely.

Cons of Slack archiving:

• The editable nature of archived channels means they’re not a secure form of data preservation. There’s still a risk of unauthorized access, exfiltration, or loss.
• It’s possible for negligent or malicious actors to act unseen in Slack—uploading a sensitive file to the wrong channels and deleting it without reporting the breach or using Slack to deliberately exfiltrate confidential data by syncing it between company-owned and private devices, for example.
• While Slack retains paid workspace data indefinitely, restrictions on channel message limits may mean not all the data in archived channels is visible to administrators without petitioning the Slack support team to release the information.
• Content in free Slack accounts is automatically purged after one year, limiting how long organizations can retain data.

An archived Slack channel is therefore not an immutable record of activity, nor a comprehensive back-up solution. Without a more robust alternative, data contained within a Slack archive is at risk of unauthorized access, exfiltration, and deletion.

Slack back-up

A Slack back-up is a more secure storage solution than Slack archiving.

Pros of Slack back-up:

• Slack back-up captures and retains Slack messages in an external repository that is under the control of the org owners or administrators, not Slack.
• Ideally, Slack back-up solutions connect natively to Slack via API to capture a complete, real-time record of all messages, including revisions and deletions.
• Slack back-up saves snapshots of data at all points, not just the final versions of messages and files in case of disaster recovery or legal discovery.

Cons of Slack back-up:

• Backing up Slack data, especially for companies with extensive communications, may involve significant storage space at additional cost and management.
• Slack back-ups may include sensitive information or protected data, requiring organizations to ensure the data in their back-ups is secure and compliant with data privacy
• Slack back-ups may have difficulty separating company-owned data from personal information shared in chats and channels. Without this distinction, organizations may be backing up more data than necessary.

Does Slack automatically archive data?

Slack does not archive inactive channels unless workspace admins use an API application to build that rule. However, Slack does archive data in the sense that it retains all messages by default for paid workspaces, and up to one year for free accounts. It’s important for admins and users to understand that, depending on Slack plan tier, these messages may not be easily accessible even to workspace owners, and any custom retention policies will override this feature.

Why Slack archive isn’t an ideal back-up solution

Workplace collaboration platforms like Slack have created a new dataset that has come to the attention of courts and regulators. Businesses that deploy these tools are expected to retain a complete record of their contents according to regulatory compliance and to meet legal discovery demands. Relying on Slack’s native archive feature to fulfill these obligations is not enough.

• Depending on account tier, archived data may not be accessible to admins without petitioning Slack for its release
• Slack does not retain a complete record of all message revisions and deletions, resulting in incomplete record sets
• Standard retention policies may not meet compliance needs for highly regulated industries
• Users are able to add and remove channels from the archive, leading to potential spoliation in eDiscovery cases
• Slack retains control of the data and can change its retention and access policies at any time
• Archiving a channel does not create a secure copy of the data, leaving it vulnerable to corruption, ransomware, and technology failures

Trust Mimecast Aware for secure Slack back-ups

Mimecast Aware helps businesses meet their compliance obligations to secure Slack conversations, capturing and securing a complete record of all messages in a search-ready archive that accelerates search and eDiscovery workflows.

With Mimecast Aware, your organization can:

• Customize and set granular retention policies for Slack and other platforms and data types
• Make data more easily discoverable with federated search capabilities
• Automate data retention and monitor from a single dashboard
• Enable audit logs and role-based access controls (RBAC) to prevent unauthorized access and mitigate negligent or malicious intent with data.

Aware’s granular data management capabilities give companies, like this Aware client, the flexibility to support their employees’ collaborative needs and maintain a positive compliance posture.

Begin archiving Slack today with a secure, cost-effective retention solution, or connect via API for continuous DLP functionality from a bi-directional archive that supports granular retention and legal holds.

Slack Archiving FAQs

What is the function of a Slack archive?

A Slack archive is simply a way to reduce clutter and streamline a Slack workspace by removing disused and obsolete channels without losing the messages they contain.

What is the benefit of archiving Slack channels?

The ability to archive channels gives workspace admins and users the freedom to organize collaboration efforts into both long- and short-term projects without worrying about inflating their channel list beyond what is manageable.

Can you retrieve an archived Slack channel?

Yes, Slack channels can be restored from the archive and reinstated. To do so, navigate to the archived channel through the search bar, click the channel name and then Settings in the open window, and select Unarchive this channel.

How do I view archived threads in Slack?

Slack embeds threaded messages into the channel where the original message is posted. The status and visibility of threads in Slack is dependent on the status of the overall channel. Users with access to the channel can expand and view the full thread at any time unless it is deleted or hidden due to the account tier and workplace settings.

How do I see old messages in Slack?

The ability to see old Slack messages depends on several factors:

• The workspace account tier
• The use of any custom retention policies
• Access to the channel where the messages were sent
• Direct messages are only visible to recipients and workspace owners in some instances
• Some Slack tiers only allow users to review messages from the last 90 days

Workspace admins can also impose custom retention policies on higher tiers that might delete messages in a shorter timeframe or retain them in a visible format for longer. Even if messages are accessible in Slack, they are still only visible to users with the right channel permissions to see them.

Assuming the messages still exist, and users have the right permissions, they can locate old messages in Slack using the standard search functionality or by browsing their message history.

Can you bulk archive Slack channels?

Bulk archiving Slack channels is not possible within Slack itself but can be accomplished using a third-party Slack app that connects via API.

Are deleted messages archived on Slack?

Deleted messages are not archived on Slack, but archived messages may still be deleted by custom data retention policies. Users can also unarchive channels in order to delete messages. Without a DLP or Slack back-up in place, any message deleted by a Slack user is gone forever.

First Published Dec. 2023. Updated May. 2024.