https://techcrunch.com/2018/10/29/signal-sealed-sender-feature-messaging-security/

Signal, regarded as the gold standard of end-to-end encrypted messaging apps, is rolling out a new feature that will further protect the identities of message senders.

“While the service always needs to know where a message should be delivered, ideally it shouldn’t need to know who the sender is,” Signal revealed in a blog post Monday.