"bcc:" won't work if people need to be able to respond to the group. but aside from that, I think that he really wants is not just a randomizer, but something

"bcc:" won't work if people need to be able to respond to the group. but aside from that, I think that he really wants is not just a randomizer, but something that explicitly flags that fact that the 'to' field reflects a random ordering. Otherwise, how are the recipients to know it's a random ordering? (that's a bit of a simplification, though. It might not be necessary if such randomizers were well-known and/or it became obvious from multiple of someone's group emails that their recipient ordering was random-looking).