The Cleantalk service that we use is generally awesome, but there was a conflict between it and the proxy nature of Cloudfront, which we are presently using for load balancing but not security (Cleantalk seems superior to that, so far). Anyway, I spoke to the Cleantalk folks about this, and today they released version 1.02 of their package (
http://custom.simplemachines.org/mods/index.php?mod=3851), which deals with issues caused by proxy servers like this.
So for all the new users who were perplexed why they were at first marked as spam, now you know! Thanks for your patience.
