Unencrypted messages in a secure session should be more obvious
Created by: pR0Ps
As mentioned here, there's no real warning when a plaintext message is received in the middle of a secure session (other than the message not having a lock icon).
Something more noticeable would be a good idea. I'm thinking some placeholder text like "Unencrypted message, tap to process", where tapping opens an explanation with a cancel/continue button.