Not the queen, but the khaleesi of workplace shade, "please advise" is the tool of both heroes and villains. When paired with a diagnostic of the issues the emailer is requesting advice on, it's a polite bid for action from someone else, which any workplace with more than one role will involve. When unaccompanied? "Please advise, because I'm not doing a dang thing about this until you do."

If "please advise" is the khaleesi of polite work phrases, "thanks in advance" is the khal, the sun and stars of work life. Though technically thanking someone for their work, it's thanking them for doing what you asked ... because you asked them to do it, no further response on their part needed.

"If I'm going to repeat myself, I'm going to point out that it's a repetition." Often accompanied by that last email being attached. Y'know, for your convenience. Should the responder fail to take the hint, the next step in incredulity is a blank response with the pertinent points of the email chain highlighted in yellow.

When intended gently, this can be a preamble to suggested future behaviors. When not intended gently, this is followed by a frank statement of the situation and the behaviors that lead to it. "For the sake of clarity, I think we should do X instead of Y, because Y is idiotic." The 'clarity' is the sentence is a reminder that if this seems harsh, it's for a good reason.

"...because regardless of whether you want to respond or not, this still needs to get done." 

"Oy, bucko. I expect you to be working on this, because I expect you to get it done." Not necessarily communication between a supervisor and subordinate, but always between someone who is waiting on a particular project's completion by a coworker.

Not an order, but definitely explicit about what you'd like to have happen.

Like, "stop it."

This phrase -- and in fact, all of these phrases -- can be used entirely sincerely and politely, but 'please note' suggests that what you're about to, uh, note should have a bearing on the actions of your coworkers. Certainly not a threat, but there's a reason there's a preface here -- plus, like any use of the word please, where there's not a direct order, there's a desire to give one.

We're beyond please note. Note it or die trying, valued team member. 

GLOVES OFF.

"I know that you know this.
You know that I know that you know this.
And yet, you believe that I am willing to do let you get away with it?
Not today, satan."

What begins as please note ends tragically when the noting ain't done. 

"Yes, you said that, and yet it has no bearing on what is going to happen." Sometimes used valiantly to make sure it is clear that a certain piece of information (though offered in good faith) is not actually pertinent, sometimes used to point out that no matter what the correspondent says, this must be done.

When offered with a cogent and helpful explanation: kind!

When offered with an imperative statement: I hope it is clear that you better get this freaking done.

"I doubt you are aware of this.
I doubt it very much.
But you really should be."

"Your email came out of the blue, and despite that, I've assisted you. Bye now."

Though there are sometimes work-nemeses who just seem to be gunning for you, more often an "as discussed" email is to ensure that there is a paper trail to the interaction. This isn't shady; this is circumventing misunderstandings.

Essentially: "For best practices, don't do that."

Still, there are worse phrasings, and this one in particular implies a range of possible ways to do things, though there is a particular way that is best. (Note, please, that it doesn't directly state that someone did it wrong.) And it might be that this is just a case of knowledge sharing. 

Sometimes considered the coldest sign-off, best is certainly more abrupt than the juvenile 'sincerely yours' or the presumptuous 'thanks' or as inversely suggestive as 'respectfully', presumably a shorter version of 'best regards.'

But when I use it, it means that the best = still me. 

Despite sounding more overtly kind than best, warmest regards is often the sweet sign off on the chilliest emails with icily polite diction.

"I'm not mistaken.
You're mistaken.
I'm correcting you."