...hence meaning is not a discrete, individual entity passed from speaker to hearer.

How can it be said the meaning is a property of the expression—its use, its context, its syntax, its content, its whatever—if Y could not derive from it its meaning, and if Z has not expressed anything? — NOS4A2

Are you differentiating meaning from information? Or can meaning be reduced to information in your scenario?

I think I would be differentiating between meaning and information.

So what you are saying is that, in addition to whatever is encoded in the sentence, there is an additional element which only exists in the actual communicative event?

How can it be said the meaning is a property of the expression—its use, its context, its syntax, its content, its whatever—if Y could not derive from it its meaning, and if Z has not expressed anything? — NOS4A2

Some would identity meaning as an abstract object called a proposition.

I utter sentence S in order to express proposition P.

P isn't a property. It's an object in its own right. This approach has the advantage of starting the analysis from where we are instead of trying to build up to it from a location we can't occupy.

This sounds just like John Searle’s Chinese Room thought experiment to show computers have syntax but not semantics. In this case, Y is just “moving” symbols around.

I met a traveller from an antique land,
Who said—“Two vast and trunkless legs of stone
Stand in the desert. . . . Near them, on the sand,
Half sunk a shattered visage lies, whose frown,
And wrinkled lip, and sneer of cold command,
Tell that its sculptor well those passions read
Which yet survive, stamped on these lifeless things,
The hand that mocked them, and the heart that fed;
And on the pedestal, these words appear:
My name is Ozymandias, King of Kings;
Look on my Works, ye Mighty, and despair!
Nothing beside remains. Round the decay
Of that colossal Wreck, boundless and bare
The lone and level sands stretch far away.” — Shelly

Consider the meaning of the sentence, "Look on my Works, ye Mighty, and despair!" The context shows both the original boasting intended meaning, and the ironic emptied out meaning turned back on Ozymandias.

I conclude that meaning is not limited to the intent of the speaker or the understanding of the listener, but permeates the whole of space and time and is affected by the desert wind and the traveller's tent, and has the power to inform even a modern philosopher.

Oh, and as it happens, it's a command, not a proposition.

So what you are saying is that, in addition to whatever is encoded in the sentence, there is an additional element which only exists in the actual communicative event?

I don’t think anything is encoded in the sentence. All of it is encoded in the interlocutors, so to speak. It seems to me the interlocutors, and not the sentences, should be paramount in any theory of meaning. Speakers and their expressions appear frequently, but not so much listeners, who express nothing.

Meaning is both embedded and embodied. It's embedded in our environment, embodied in language and gestures, interpreted on many levels from the cellular to the semantic. It's arguably the fundamental stuff of life, much more so than molecular structures. That's the rationale behind biosemiotics.

This sounds just like John Searle’s Chinese Room thought experiment to show computers have syntax but not semantics. In this case, Y is just “moving” symbols around.

I suppose there is a parallel, but I don’t think it is says anything about the listener, who has semantics.

Oh, and as it happens, it's a command, not a proposition. — unenlightened

Ooooo.... that's pretty good.

Meaning-as-command: of course you can lie about it, but there it is!

How can it be said the meaning is a property of the expression—its use, its context, its syntax, its content, its whatever—if Y could not derive from it its meaning, and if Z has not expressed anything? — NOS4A2

Without getting clear about any antithetical claim (or what criteria are being used to judge), let's take the definite position: meaning is a property of the expression. One corollary is that, X has something more than Y does, than Y ever could. One imagining is that this is an object--as @Banno was trying to point out--that the explanation would be based on the picture of how we treat "things" (say, here the word, there the thing). However, the claim is true if we shift the "thing" which X "has", to be: the responsibility. The "property" of the expression is not imbued by X and not Y (X's "meaning"). It is simply that Y cannot be held to account for speaking X's words (or could, only unjustly). Y will point to X (unless Y is quoting, etc.) The extent X "means" them is the extent X will stand up for them. X does not "use" them any more than Y does. That they are X's "expression", and not Y's, is only that X is the individual who owns (up to) them (or disowns them). The "meaning" is also not "in the expression" (taken as: the words); the question of meaning does not come up unless Z has to ask, and then Z asks X. Without any X, Z may conjecture from evidence (context, etc.), but Y cannot help; in fact, X may know less than Z can confidently piece together. We could even say this interpretation is an expression of Z.