@fencepost @GossiTheDog I think the inherent 'flatness' of Signal, and other non-federated IM systems is a weakness in that it fails to make use of the information you get for free from the tree structured nature of the DNS. If the other members of the group had all been on the republican.org, or whitehouse.gov server (or a mixture), then the presence of a jeffrey.goldberg@theatlantic.com would/should have been glaring obvious.

@fencepost @GossiTheDog It is a very poor UI decision to hide information from a user for the sake of convenience which would allow them to make security decisions. This is not restricted to Instant Messengers.