Hi! An official announcement from Zach Latta has been made in the Hack Club Slack.
We're moving to Mattermost now and we're trying to export all messages, DMs, etc.
Disclaimer: I am a member of Hack Club's Slack and NOT a working personnel there.
Not sure if you saw this, but another user pointed out that Mattermost is moving to limit self-hosted instances to 1,000 users:
https://forum.mattermost.com/t/solved-is-there-any-limitatio...there exists a fork that is basically limitless
https://framagit.org/framasoft/framateam/mostlymatter so if that ever becomes a problem you just swap server binary