Google Groups has a spam filter. A very finicky spam filter. It flagged a bunch of posts from Craig and held them for approval or discard. I just noticed and cleared them today during my first visit to the Group site in several days—Groups apparently doesn't send administrators email about flagged messages. Or maybe that's a feature I need to configure...
Anyway, let me know if you send something to Ipse Dixit and you don't receive a copy in your mailbox. Then it's likely it is being held for approval.
I believe that Groups' spam filter is "trainable," which means that over time it will become less likely to flag messages.