It would be useful to have some special types of channels for particular use cases:

• transient channels - these would be used for temporary messages that don't need to be retained over the long term; you could configure a persistence period for them but after that period old messages in said channels would be purged (not logged)
• read-only channels - e.g for a leader to send out important messages to everyone but not allow discussion
• mandatory channels - a channel that all users are automatically subscribed to and that they are not allowed to unsubscribe from (e.g for site-wide announcements). It seems #general already does this?

Perhaps these could be options that can be toggled or adjusted on the channel settings page? I could see it being useful to be able to combine them too, e.g making a read-only, transient, mandatory stream for announcing site-wide maintenance. Thoughts on this proposal?