Currently normal moderators can set the moderators inbox to “Watching” the topics. In this case they are able to receive emails about posts ended up in the queue awaiting approval (based on the notify about queued posts after site setting).
For category moderators, however, this is not possible. They receive the red notification on the site, but they will not receive any emails notifying them that there are posts in the queue.
Receiving emails as well as onsite notifications could encourage the use of category moderators instead of normal moderators.
Does that mean that this is a deliberate choice (not to notify category moderators by mail)? Category moderators are a useful role, different from normal moderators and I’d be interested about the rationale for depriving them from mail notifications. It makes them work more difficult because they have to either manually check on a regular basis or hack a notification system on their own.