Slack – Restrict Who Can Post on a Channel

It's possible to batch delete messages through the Slack archives page, but this only lets you delete one page of messages at a time and does not delete any corresponding file uploads.

A better solution that deletes all messages from channels and/or groups, including file attachments, is slack-cleaner.

In order to store and print messages from a channel you use the export feature in the client or develop a script that uses the web API.

The export feature works fine, however there are a few constrains:

• can only be done by admins or owners
• only works for public channels
• the format is JSON (one file per channel, each message is one element in a JSON array)

See here for further information on the Slack help pages.

I also found a Slack App called Export that allows to export the full content of a channel for storage and later printing. This app supports exporting for any channel the user as access to including private channels. Messages can e.g. be exported in HTML for printing with the browser. The app works fine, but the output quality is a bit rough and seams to lack images and conversation of Slack link syntax to HTML.

Another approach is to develop your own script. You only need to read all messages of a channel directly via web API (with conversations.history]3) and then process it further (e.g. convert to output file for printing). That will work for both public and private channels, but obviously requires a bit of coding.