I'd like to set up some email addresses for kids. In order to control their email carefully while they're still young, I'd like to be able to set up a junk mail filter that puts "@*" as a low-priority blacklist entry, then add the addresses they ARE allowed to email as higher-priority whitelist entries.
I understand this is for incoming email only, but that's half the battle, with kids: this way I can ensure 0 spam emails incoming, and that they can exchange email only with those I've explicitly allowed. Applying whitelist/blacklist filtering to outgoing email would be a follow-up feature request.
For now, can we please just have the ability to add "@*" as a catch-all filter on a black-list? That seems to be an easy feature to add.