Importing from Slack

A workspace owner can bring channels, message history, threads and reactions over from a Slack export. Nothing is sent to anyone, and nothing in Slack is changed. You always see a preview first, and nothing is imported until you confirm.

Before you start

• Only an owner can import. Admins see a note asking them to ask an owner.
• Invite your team first. People in the export are matched to CM Chat accounts by email address, so anyone who already has an account keeps their name on their old messages.
• If your workspace deletes old messages automatically (see Security settings), imported history older than that period would be removed again. Turn retention off first if you want to keep it.

Make the export in Slack

1. In Slack, an owner opens the workspace settings and chooses Import/Export Data, then Export.
2. Pick the full history.
3. Download the .zip file Slack prepares. It can be up to 64 MB.

Slack includes email addresses in the export only when an owner of a paid plan makes it. Without them, nobody can be matched and every author appears by name only.

Import it

1. Open Import from Slack in the admin console.
2. Choose the .zip file and click Upload and check.
3. Read the preview. It shows how many channels, messages, matched people and reactions it found, and lists anything that will be left out.
4. Click Confirm and import, then confirm that it is you if asked. Click Cancel instead to stop.
5. Watch the progress bar. If you close the page, the import carries on and you can come back to it.

What comes over

• Channels. Each Slack channel becomes a new CM Chat channel. If the name is already used, -slack is added to it, so your existing channels are never mixed up with the import. You become an owner of every imported channel.
• Messages and threads. Messages keep their original time and order. Thread replies stay under the right message. Slack formatting is converted to CM Chat text.
• Reactions. Kept, but only for people who match an account.
• People. Matched by email. Nobody is invited and no account is created. People without an account appear by name only.
• Nobody is notified. The import sends no emails, notifications or webhooks.

What does not come over

• Direct messages and group direct messages.
• Files. A message that had a file keeps a line naming it, but the file itself stays in Slack.
• Joins, leaves, topic changes and pins.

Very long messages are shortened to fit the 8,000 character limit.

Earlier imports are listed at the bottom of the page, with their status. Imports are recorded in the audit log.