Wayne,
That is not currently the action that my installation is doing. I have checked and unchecked “Allow Anyone To Post Via Email” setting box, however, it does not seem to make any difference. I am using the plugin in “Curl” mode, and have set the default poster to another user within the system. I have had multiple people “test” it for me (addresses not on the list), and in every event, they are able to create an “active” post on the site. I have found that the messages may not be picked up on the first attempt (due to matching), however, subsequent pickups from the mailbox seem to be picked up normally, then processed and posted.