When a new user is invited to a private channel, s.he can access all the past logs as if s.he was a member of the channel from Day 1. I see this as a sort of privacy pitfall, as you have to control your language thinking of who may be invited in the future. That's not exactly what I'd call a private discussion channel.

My use case is that we are using mattermost to discuss our research project. I can perfectly imagine how we discuss together about a concurring project and then later introduce a postdoc coming from that group. That may have really ... unfortunate outcomes.

It would be much more natural and less error prone if users could only see the logs produced during the period where they were a member of the channel.

Of course, my proposal is not a secure protection because a channel member could always leak what is said in here. But that's already better than the current situation where everything is leaked by accident on a systematic manner.

Thanks for this great tool,