Timo,
I have a wild idea for a feature that is somewhat unusual, would be very powerful, and easy to implement. What I want is ...
Special folders that when someone drags a message into them - it pipes the message into a program.
The reason I want this is - for example - reporting of spam. Suppose you want everyone to have a spam-missed folder so that if a spam gets through then the user drags it into the spam missed folder. But instead of storing it there it executes a program and pipes the message into it. In this case a learner program for the spam filter. The folder would be "write only" and attempting to read the folder would generally look like it was empty. Setup would look like this:
executable-folder spam-missed { command = /usr/bin/sa-learn spam user = spamd group = spamd create_folder = yes accounts = * }
The "create_folder" command says to add the folder to the users lists whether or not it is physically there. The folder appears even if there is no real folder. If it is "no" then it only exists if there is a real folder. The "user" and "group" is of course the UID and GID to run the "command" as. The "accounts" determines which accounts are affected. Default is everyone.
Other uses is to control blacklists and whitelists. Dragging a message into the blacklist folder runs an executable that adds the sender to a blacklist, or a whitelist, or controls settings etc.