This came up last night in-session, and RAW, I do not believe the verbiage of the Message Cantrip matches RAI. The issue arises due to the fact that the spell seems to be two spells in one.
You point your finger toward a creature within range and whisper a message. The target (and only the target) hears the message and can reply in a whisper that only you can hear.
The word "target" here has a specific meaning, as does how that target is acquired, ie, you "point your finger toward a creature". It is assumed you must be able to see it to target it, as established elsewhere in the rules.
However, this is partially overridden in the second usage context:
You can cast this spell through solid objects if you are familiar with the target and know it is beyond the barrier. Magical silence, 1 foot of stone, 1 inch of common metal, a thin sheet of lead, or 3 feet of wood blocks the spell. The spell doesn't have to follow a straight line and can travel freely around corners or through openings.
There is nothing in the second paragraph that says explicitly that you no longer need to "point toward" the creature to identify the target; only that you don't have to "see it", and must be "familiar" with it, and that the spell can find it's own path if there is one. Are we to just assume that EVERYTHING in the first usage context is moot? 'Cause the way rules stack, we shouldn't, right?
That's the crux of the issue: do you still have to "point toward"? If so, that very much changes how this spell works in the field!
One interpretation is that the spell still intends that you know the location of the target behind "the barrier" (singular, and important note!). You know it's behind that table it flipped for cover. You know it's behind the bar it dove behind. You can't see it, but know that it's behind "the barrier", and can target it, purely because you are "familiar" with it. So, if there is a SINGLE barrier in the way, and I know they are behind it, I can target them by pointing at them behind the barrier, if I am familiar. That seems logical that the spell is clearly at least this powerful, and reasonable for a Cantrip.
But, what if the creature ran around a corner, down an unknown twisty corridor, perhaps several corners away (ie multiple barriers, but still an open path to target)? It could easily be within 120' range, but I would have no idea where to "point toward". Yes, I know the target (ie I'm "familiar"). Yes, there is a path to them. Yes, they are 120' in range. But I honestly don't have a clue where they are. They could be anywhere within a 180 degree arc on a battlemap from the caster's relative position, ie, impossible to "point toward" so as to target with 100% certainty. But, they could be within 120', and while there may be 30' of solid rock separating us as the crow flies, the spell says that the magic will go around corners if there's a path to target!
That seems a bit powerful for a Cantrip...essentially turning it into a 120' Sending spell if there's a clear path to target.
I can see really good arguments on both sides saying that this spell should or should not work in this case. I'm torn, so wanted to post the question here and let the community vote an answer to the top!
So, can I use Message if I don't really know where the target is, and therefore can't "point toward" them? Or is the fact that I'm familiar with them, they are in range, and I have a path to target around the barrier (or barriers) blocking us, enough for this Cantrip?