Ok, Alice, here comes the translation. The message does say:

Notice to inhabitants of planet number 3 orbiting star 42p42. Stay where you are. Refrain from sending insecure vessels towards planet number 4, or any other galactic destination. Stay on your planet.

Repeat: STAY ON YOUR PLANET. DO NOT BOARD. DO NOT LAUNCH. STAY PUT, UNDER ALL CIRCUMSTANCES.

Your primitive spacecrafts are not voidworthy and your type of species is not welcome out here. We’ve enough trouble managing as it is. The last thing we need, for the next couple of millennia, are newcomers. You’ve got a fine viable planet, make the best of it.

A dark energy barrier has been erected, to inhibit further incursions into territory regulated by galactic interspecies convention. Any vessels trying to breach the barrier will be turned into dark matter. In use you haven’t deciphered dark matter yet, as your primitive mode of propulsion suggests: Getting turned into it equals the most final way of becoming dead, gone, non-existent.

Wow. Are you sure, Bob? This sounds like the mother of all pushbacks. Do you really think there could be someone out there able and willing to erect a dark energy barrier, just to keep us on our planet? Any chance this translation might be a little,… don’t know, too extreme? Any chance they just want to warn us, that space travel is dangerous?

Alice, my translation might have its weaknesses, perfectly ready to admit as much. It’s first contact after all. But the authors of this notice seem very keen on getting their core message across. They made very sure to make it easy to decipher. And the basic principle isn’t that alien. Fences to stop wannabe immigrants, that’s what one does, to keep a nice neighbourhood from filling up, right?

Bob, honestly, do you really think the authors, them out there, that they would consider the likes of Jeff Bezos, Richard Branson or Elon Musk some kind of boat people, who can be pushed around? And there are so few space tourists, why bother? Whichever advanced civilisation rules out there would certainly have the means to sustain a couple more folks?

Well, Alice, and since when does having the means imply wanting to share them? To me, this notice sounds more like same old. Up there might be just like down here. Not nice, but hey, not nice has always been part of the game, right? And talking of not nice: What do we do next? How do we tell the boss? He’s sure to hate this notice, and I sure don’t want to be the messenger getting fired for delivering it. How about you?

Are you mad, Bob? He’d be sure to freak out. And if he took the notice seriously, it’s not just you getting the sack, all our jobs would burn faster than stage 1 rocket fuel. No way. We need to think of something.

…

Let’s call it the first space spam. And where does spam go? That’s it, good boy Bob!