relay

Queues envelope for its recipient. When this returns, the envelope is ordered after every envelope of the same sender for the same recipient that was relayed before (MailboxRepository, docs/transport-ordering.md).

device must be authenticated for ProtectedEndpoint.SEND_MESSAGE and be exactly the envelope's sender; otherwise EnvelopeSenderMismatchException is thrown and nothing is queued (S1, docs/server-authentication.md). The payload is never inspected.