It's interesting how everyone thinks they're the first person to make the joke.
Not much different than going "haha, I thought it was about the Elm tree for a while!"
I'm starting to think it's just a way to signal to others that you know of an email client that last had a stable release 12 years ago that most people haven't heard of. Maybe there should be a way to wear this badge of honor in your profile instead of making the same joke, though.