Dear Anon 42,
That’s a screen cap of the (old, now that Tumblr’s changed their layout) message module on our dashboard—it shows up when we’re logged in to Tumblr, and that’s the only place it shows up. We don’t know even know if it’s possible to get something like that to display on the blog itself. Maybe there’s a theme somewhere that has a feature like that…?
Oh, but don’t worry about swamping us! The only hard part about having so many letters is having to screen cap and archive them all, so we usually save that for weekends, but other than that, it’s pretty easy to put the letters together. Maybe if we were a hand-drawn ask-blog things would be different, but for now, we’re good. :>