I’d like to see a feature that could send out periodic email (configurable, but say every 6 months) to all the users (or maybe just inactive users who have not logged in for X months), requiring them to click on the link to keep their account active. This would ensure that users who should no longer have access to the login would be culled. This is useful for users who are given access to a multi-company owncloud installation, based on their employment to a certain company, but are no longer employed by that company. If they no longer have access to their old employers email account, they will be deactivated from the own cloud repository. Deactivation is preferable to deleting an account.
Note, the email link should NOT require the users to login. Training them to click on email links and enter their credentials would be a bad thing.
I have to review all users manually and delete users that I don’t think should be there.
This sounds like something a market app might be up to providing.