Is this a question or a (polite) command? [duplicate]

I've recently written an email asking someone to do certain things. At the end of my email I ask my correspondent to let me know that they have received my email. I wrote this -

> Please can you confirm that you have received this email.

Although this clearly has the form of a question, the sense is not so much a question as a (polite) command. For this reason I've found myself wondering whether this line should end with a question mark, an exclamation mark or just a simple full stop ? My instinct is the last of these.

The Chicago Manual of Style, sixteenth edition (2010) refers to these expressions as "requests as questions" and takes the position that they need not be punctuated with a question mark:

6.69 Requests as questions. A request disguised as a question does not require a question mark. Such questions can usually be reduced to the imperative.

Would you kindly respond by March 1.

or

Please respond by by March 1.

The Oxford Guide to Style (2002) takes a similar position at 5.8.1 ("Question mark | Typical uses"):

Do not use the question mark when a question is implied by indirect speech. It may—but need not—be used when a n apparent question functions as a request. Here the question mark seems more polite than a full point:

Would you kindly let us know whether to expect you?

I wonder if I might ask you to open the window?

These same sentences with full points [that is, periods] replacing question marks would imply a virtual command, perhaps even a degree of menace. However, statements framed as questions out of idiom or politeness do not normally take question marks:

May I take this opportunity to wish you all a safe journey.

Will everyone please stand to toast the bride and groom.

In some contexts this form may be considered excessively formal or stilted, in which case the sentence can be framed instead as declarative sentences:

I {take this opportunity to} wish you all a safe journey.

Please stand to toast the bride and groom.

Both Chicago and Oxford agree that a question mark is optional in a request such as

Please can you confirm that you have received this email.

But whereas Chicago doesn't pursue this question of punctuation any further, Oxford rises the possibility that the declarative form of a request as question (indicated by closing with a period instead of with a question mark) may strike some readers as impolite, unduly bossy, or even menacing. In the next sentence, though, Oxford seems to acknowledge that writers may frame statements as questions in the first place out of politeness—in which case such statements "do not normally take question marks."

The problem, of course, is that one person's attempted politeness is another person's phantom menace. Perhaps the safest course under the circumstances is to express requests in an unmistakably direct declarative form and depend on judicious use of "please" and "thank you" to convey your desire to be polite:

Please send me a note confirming that you have received this email. Thanks!

It is a polite request but it is stated as a question. A full stop will do. A question mark would seem overly accurate and out of place. The usage is often of the form: "Please confirm that you have received this email."

I know enough snarky emailers that would report that they could confirm but that they would rather not.