For the purpose of completeness let me address your question as if it applies not only to email but also to regular speech. I have heard people who talk like that! There is nothing wrong with such usage. Rather than rude, you would be perceived as highly polite or formal.
Could you please,
if you could please,
may I request you to please,
would it be possible for you to please,
would you be kind enough to please,
would it greatly inconvenience you to please, etc
are just excessively polite ways of framing a request or order that usually needs just a simple 'please.'
Such phrases are a remnant and reminder of the so-called 'age of manners' when it was considered rude not to use such phrases in polite society. The novels of authors like Jane Austen have both satirised and immortalised such usage, which is still appropriate in certain situations, especially when dealing with somebody who expects and values formality and politeness to the point of taking offence at an informal tone of address. However such excessive formality of language used in everyday social situations can irritate modern and forthright persons who consider it unnecessary and circumspect:
Mr.A: would you please be kind enough to pass that file, please?
Mr.B simply passes the file and thinks, what weirdly polite language for this day and age! We dont speak like that here. He must be such a circumspect person.
It is part of simple courtesy to couch an order as a polite request so as to show respect to the other person, but being excessively polite can have certain social and professional drawbacks, in my own humble experience.
Some people including myself are just naturally formal and polite which is no bad thing, but we might be perceived as cool, cold, remote, aloof, arrogant or detached though not outright rude. This is especially possible when highly polite usage is not naturally part of the conversation or communication of that social / professional milieu. Some people actually prefer a rudely forthright person to an excessively polite one!
Mr.B later tells Mr.C: his excessive politeness gets on my nerves! I much prefer plain talking individuals with a bit of colloquial warmth and the odd rude phrase, if you get my meaning...
A lot depends on whom you are addressing and the level of formality that is native to that particular group and the specific interaction. To sound warmer or less formal, just drop the polite phrases and use simple 'please' with your request/ order/ assignment!
Note 2: some people including movie dialogue writers and comedians have juxtaposed excessively polite phrases with rude/ vulgar expressions to convey exasperation, sarcasm or just plain humor:
Could you please kindly shut your €&*@%$ mouth and let me think my way out of this mess you have kindly got us into!
Would you be kind enough to please tell me, Mr. D, why exactly, in your esteemed opinion, you behaved like a €&*@%$ fool?
With your kind permission, may I please take the liberty of shoving this €&@%$ document down your €&@%$ throat, unless you could be so kind as to tell me what my €&*@%$ mother-in-law is really up to!