It's good, because they've copied most of the good parts from Slack. 😉
Multi-team functionality is the best thing. We can have many workspaces / teams and you only need one set of credentials to access everything. We have an internal team for confidential business and another team for chatting with external stakeholders.
From what I learned hosting a Mattermost instance is pretty easy and requires little configuration. I suggest everyone to check it out if Slack pricing gets too costly or your compliance requires you to control all your data.
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