That Evolution mail caching behaviour is really sketchy. I wonder if it could be used for an exploit in the right scenario. If nothing else, it’s a good way to make an email that looks completely different depending on which client it’s opened in.
I love this, thanks for sharing. When I failed to get a measurable time difference myself I was worried I might just be doing something wrong and it'd get flagged the moment I published my research, so it's great to get confirmation from other people.
With the single-packet attack, you look at the order that the responses arrive in, instead of the time they take to arrive. Since the responses are on a single TLS stream, they always arrive at the client in the order that the server issued them in. Hope that makes sense!