Agree with Tobias on these things. I have been running with them off, but turned them back on as I’ve got a few new mods now.
I think that they are set up to be clever and only PM those mods who’ve visited the site since the last one. I get that, but it does look a bit confusing from the perspective of the most frequently visiting mod!
To get to these settings that control this stuff, search for notify in the settings.
There are some other somewhat counterintuitive interactions that go on with this. For instance, having a new user in the queue for X hours seems to be considered a flag, so if you set the flag notification time low you’ll get double notifications:
