Add an option to show users who left recently for admins of public mucs
When permissions to view JID is set to moderators only, there is no easy way currently to ban a spammer who joins, posts spam, then leave immediately and repeat this behavior. The only way to get JID of such spammers is running poezio which displays full jid.
So if a user has permission to see jid in a semi-anonymous muc, they should see a list of users who left in 24 hours and make this duration configurable.