Prompt to invite a user to a channel when you mention them
In Slack, when you mention a user within a channel but they are not part of that channel, Slack alerts you to this and asks if you would like to invite that user to the channel - this would be an incredibly useful feature in Mattermost.
This is currently on master and will be in the 2.0 release (February, 16th)
Russell Grocott commented
Is this feature documented?