Yeah, it's a bit flaky so far.
It technically works after you reload the inbox from your email client a few times, but honestly, when I get back to this as a serious part of another project, I'll rewrite most of the code to make it more robust.
I plan to integrate a similar concept into Eve, the main product I'm slowly working on, a tool for closed community networks.
DMs will definitely be supported, as will group conversations.