I often face the following scenario:
I need to ask for a document, a piece of information or make a request to an employer of a company/organization whose job includes responding to people like me. For example, it might be a secretary at my department's in university, or it can be an employee in the company where I bought my health insurance, etc. If I ask for the thing (information, document, etc.) directly, such as
Dear blah, I need blah blah. Could you send it to me as soon as possible, please.
I feel like I am being rude, and especially if I have a hurry, which is generally the case, they might not respond to me quickly since I am not explaining why I need that thing. Of course, there is also the possibility that they might never answer at all, so there is a real risk of waiting for an email that will never come.
But if I say
Dear Blah, I have doing blah blah, but to do blach, I need blah blah as soon as possible, so could you send it to me, please.
I am explicitly explaining myself to another person which I hate doing it, but just to increase my chances of getting a much quicker response, I do it. But, when I explain myself explicitly, the email becomes long and it takes time to be understood by another person.
As if all of these are not enough, generally, the people I am talking with are not native English speakers, so even if I compose a perfect email, the other person might not understand what I am saying and how I am saying, fully.
In such situations, what are the best strategies of composing emails that might minimize the response time, are polite and explains the requested document/information for the sender clearly?