[Galadriel55]

There are a few point that must be considered here. Firstly, Elrond did not, as it seems is assumed here, know that Denethor posessed a palantir. This changes things up a bit.

Secondly, Elrond would have sent messages as much as Celeborn would have, ie he would not have. Well, possibly Elrond has more chance of that. Third Age Elves were estranged from Men (or, rather, the Men from the Elves), and there was little contact between them. Now Elrond, unlike Celeborn, welcomed travellers to Rivendell, and when he sent out scouts before the Fellowship started out he gave them messages for the rulers of the other lands - but to do so on a regular basis?

Moreover, Gondor and Rohan estranged themselves from Elves. Gondor once used to be "Elf-friendly", but looking at Boromir and Faramir's attitude they are not much better than Rohirrim now in their relationship with Elves.

And what kind of "valuable information" could he give? That the Nazgul are over Anduin? Duh. That there are dark things hiding in the wilderness around? Big deal, no news. That orcs are massing in the Misty Mountains? What use would that be to Gondor?