Naw it's a good question! It was a thing we had going quite a few years ago. I honestly can't remember the specifics of it, just that we were penpals with Jelly XD Nephila: Do you remember the specifics of this?
It was a part of figuring out the email system and keeping it up to date with current emails. Helping to test the email function.
Those who got the button replied back to the emails so they knew who it was reaching and who the emails weren't getting to. Also I think there were some surveys done through email just to keep traffic flowing. Stuff like that.