Chances are they are either posting extremely fast, such as clicking reply, pasting something and hitting the reply button within 3 seconds (this is a site setting).
Or, they are getting picked up via the Needs Approval queue.
Also see
Chances are they are either posting extremely fast, such as clicking reply, pasting something and hitting the reply button within 3 seconds (this is a site setting).
Or, they are getting picked up via the Needs Approval queue.
Also see