I am reading a business e-mail correspondence and I see a sentence like this:
Please help scan us a copy of the cargo receipt.
Of course, I take it that it means the following, only in a more polite tone:
Please scan us a copy of the cargo receipt.
Grammatically speaking, I don't think that the first version has any mistake: the verb "to help" is transitive, so we can assume, for the moment, that the phrase "scan us [...]" is its direct object.
In terms of usage, however, I'm no longer sure. I don't remember ever seeing the verb "to help" used this way - i.e. to add politeness. I have little experience with business correspondence.
Would somebody be able to enlighten me about this?
Unless you are actually helping someone to accomplish a task they can't perform without your assistance, the 'help' in your example is unnecessary. It's not a way to make something more polite, it's just superfluous. If the writer wanted to be more polite s/he could have said, 'Please help us by scanning a copy of the cargo receipt (and, I presume, sending the scanned copy on to them).
Again, 'please help + verb' as in your example is only correct if you are actually be asked to provide direct assistance: 'Please help me scan this document; I don't know how to operate the scanner.'
I hope this is helpful,