This is the line of text in the email:
“The new user x was automatically silenced because multiple users flagged x’s post(s).”
In this instance the user was automatically silenced because the new user typed too fast - not because multiple users flagged the post.
(The site setting ‘Notify mods when user silenced’ is ticked.)
Installed version: 3.6.0.beta2-latest (f51960287f)