Hi @WalterKidder,

Unfortunately, "pre-moderation" is not available as a part of Canvas at this time.  You can, after the fact, moderate a student's post, but I know that may not be great depending on the severity of the issue of each post you'd need to moderate.  I'm in higher-ed, so luckily issues with students posting indecent content hasn't been much of an issue for us in our 10 years of Canvas use.

Now with that said, there is an existing Idea around this topic, and it's been assigned to a theme, which means it may be up for voting when the next period opens up (soon, I believe).  If the theme is selected, there should be some development (though not every idea) within about 6 months of that.

Hope this helps a bit, even if it's not the answer you were hoping to get.

-Chris