Missing Feature/X-Command to enable/disable Mail delivery
One of our users managed to subscribe members to a schleuder list in a way that mail delivery was disabled for each of them (I don't know in details how he/she managed that).
There seems to be no way to clean up this situation if your only access to the list config is via X-COMMANDs. Schleuder-CLI and schleuder-web allow setting this flag.
This is either a gap in the documentation or indeed a missing feature.