Brian Vogel writes: "OK, but I still don't understand. My understanding is that it is not possible for members of a group to block special notices by e-mail under any circumstances, even if they're "no e-mail." Am I mistaken?"
It appears you may be mistaken, Brian. "No email" means exactly that; no Special Notices or any other messages.
That's why the option to have Special Notices only. We had groups moving and making other changes and realized that a number of members were being lost or otherwise missing important information because there was no way to contact them as they were set to 'No email'.