Kindly sounds like they are trying to effect an attitude adjustment on the way to copying the email. Kindly do not address me in that tone of voice. It's more authoritative. Please is just a place holder, almost. Kindly puts too much thought and emphasis on it. Please implies doing it as a matter of course. Kindly silently adds "you ingrate!" to the end of the sentence.

Eta - i love these kindsa discussions! My recent facebook treatise on "your an idiot" was remarkably well-received.