Update: (Originally this was a comment, but I thought it was worth sharing here at the top.)
In the original question, I asked if there was a polite, socially-acceptable way to ask an Indian co-worker not to use the phrase "do the needful", as I didn't care for it.
In the years since I asked this question I've asked many people about the phrase. To the Indians I've asked in-person, it's not rude in any way. To Americans I've asked it varies anywhere from "I don't like it, but I don't mind it" to "It's very rude and makes me angry when I see it".
Through a long series of edits the question morphed and I wasn’t able to delete it because it had upvoted answers. The question, as it stands now, has no other answer.
I guess, though, if you're non-Indian and you find it rude, or if you're Indian and you've never realized someone might find it rude, this post may still have merit. Hopefully it does. It certainly has gotten a lot of views. Best wishes, folks.
End Update. See below for what's left of the actual question.
"Do the needful."
It's a phrase that I've only seen used in email, and I find it . . . presumptuous (maybe even rude). Regardless of prefacing with "please", one is commanding rather than asking for assistance.
I've only seen it used by those of Indian origin, so I've simply not mentioned it at all rather than worry about any cross-cultural offense that may come of bringing it up.
But still, I don't understand why it's used. Why not request rather than make two statements, one factual, one imperative?
For example, why would one use:
- I'm told you have Jane's email address. Please do the needful.
instead of,
- Would you send me Jane's email address?
Best Answer
Do the needful is Indian English, which has been covered on ELU.
If you're only interacting with other speakers of Indian English then feel free to use it, but avoid it in any other contexts (most Americans and Brits will think it's quaint/uneducated).
In general, the "standard" form is do what[ever] is necessary, but in OP's specific context most likely nothing like that would be used anyway. If you've just asked for an email address, it goes without saying that you want the other person to do whatever is necessary to give you that information.
I may be wrong, but I have the impression that for many Indian English speakers, "Please do the needful" carries a subtext of "This problem is too complex for me to understand or resolve myself, but I have complete faith that you will be able to deal with it, because you are very skilled in such matters"
As I said, Brits and Americans wouldn't normally use any equivalent for such a trivial problem as finding someone's email address. But if the request was for something more challenging (and crucially, if it was from a manager to a more junior worker), "Do what[ever] [you think] is necessary [to solve this problem]" might be perfectly normal. The implication there is that the manager is authorising the junior to do things he might otherwise not be "permitted" to do (in effect, the junior is being temporarily "promoted" for the duration of the problem-solving).
In that context, it should be clear that (to Americans or Brits, at least) any such phrase would probably be considered offensive/cheeky if addressed to an equal in the workplace (if the person asking isn't senior enough to confer temporary authority on you, they shouldn't be speaking to you that way).