I'm not completely sure this is a great idea. If some one posts spam to a thread
that I subscribe to, said spam gets emailed out to me (and everyone who is
subscribed).

This could easily be stopped by just sending a message stating that a new post
has been made.

Also, I have been using the red triangle to report posts that are probably in the
wrong place and just today I actually read the text underneath the text box.

Apologies if that is an inappropriate use.