According to Dan Widdis, who took time out from being a tourist in NYC to figure this out, my message were stuck in Google Groups' spam hold until he released them. He didn't know why, since the group settings are not to require moderation of members' messages. Under the circumstances, he didn't pursue the matter further, and I wouldn't have wanted him to use more of his vacation time on this than he already had.
That's why everyone got three copies: the one I sent to Dan with a request for him to send it out, and later the two I sent to the group that were stuck and that he released. The content of all three is the same.
I just hope the scenario doesn't repeat itself with the list of definitions 30+ hours from now.
Efrem
P.S. If you're reading this and you haven't yet sent in your def of MAIKO, please do!