You don't trust that third-party server with any information, it simply makes the initial link between the two parties, like a DNS, that it needs to send the en

You don't trust that third-party server with any information, it simply makes the initial link between the two parties, like a DNS, that it needs to send the encrypted information to. An evil relay server could not send the information, or send information to the wrong server, but neither would cause data to be lost because of the encryption.