Samphappalāpa is often translated as idle talk or idle chatter.
It is wrong speech and thus best avoided. Idle can be seen as irrelevant, lazy, without purpose, or gossiping but gossiping has it's own category and is not included here. It seems that it is often understood as pointless talk. Consequently some people might try to avoid talk that is not to the point. But talk that is not to the point, small talk, can be a way to connect socially and avoiding it might make it socially a bit awkward. And so there are those who do engage in small talk while seeing this as a transgression. Either way there is then some friction. If this is the case I would like to point out that the texts indicate small talk was used by the Tathāgata. And saying things like 'bless you' or 'be healthy' to someone who is sneezing is accepted, even though it doesn't help against the sneezing. It is just customary and not doing so could create a not so useful distance. Samphappalāpa is always wrong speech, but whether it needs to be understood as idle that is a different thing.
Sampha (adj. — n.) frivolous; nt. frivolity, foolishness.
Samphappalāpa is listed as frivolous talk, which indeed is not different from idle chatter. But we should also look at AN 10.211 where a list is shown of what samphappalāpa entails:
Theorizing untimely, theorizing not about the essence, theorizing for unsettlement, theorizing without principles, theorizing without discipline. The speech from the talk is with non-situational hedging, not by time, without arguments. Unlimited hedging, put together for unsettlement.
These are with the intent of being undermining, unsettling (hedging is used to express ambiguity, evasiveness) which involves some dishonesty, and thus is the speech not idle. Hence does frivolous not fit and is it instead of foolishness's foolish speech, speech to fool. But such speech can be done while not being that aware of it, f.i. when done out of habit, so then rather than dishonest or foolish it is deceptive. Which helps as 'fool' was already taken by other translations. And deceptive, says the dictionary, can mean unprincipled, which is one of the items in the list.
Palāpa prattling, prattle, nonsense; adj. talking idly, chatting, idle, void.
These words are seen as negative and gave the impression it being just about the content (idle, void). And thus could deceptive chatting be interpreted as if chatting is being deceptive in nature or that chatting, being already no good, has this worse variant were it is here about. So let's look a bit further. Palāpa reminds of palaver (resorting to other Indo-European languages can sometimes help). And palaver is by some seen as a conversation, discussion, negotiation being idle or fruitless, while by others it is taken as a fuss or bother. This didn't solve a thing. But palaver comes from the Portuguese palavra ("word") and with that we can play a bit.
Samphappalāpa could then be 'deceptive wording'. And this fits. It shouldn't have been seen as about idle chatting or nonsense as it was never about the receiver. It is about the ripening of action (heading towards a good or bad destination) and thus about the action of the sender who, led by greed, hate and delusion, is undermining the communication by means of deceptive wording, for something they believed was worth it.
Hence is small talk not automatically included, nor are talks about dhamma automatically excluded. It depends.
Pāḷi-English
Samphappalāpa deceptive wording.