I mostly agree with Patrick, and to supplement his post with one more suggestion, I think most of these category of "behavior" memos have no business going to all employees. They should stop at X level of management, which should be entrusted/empowered/delegated to make the necessary changes within their purview. One of the biggest reasons these generic communications suck is because they're generic.
Fix the management problem and you largely fix the communication problem. For the rest (benefits changes, business strategy, etc), the exec whose name is at the bottom would be well served to be as transparent and honest as possible, and for sensitive topics to include formal feedback/Q&A paths to clarify any uncertainties. There is a huge perception gap between levels of employees and it's literally the case that individuals at different levels in the hierarchy (or different LOBs/divisions) have no idea how to relate to one another; what usually happens is that they freeze and avoid engagement, which only hurts the company.
You really get at the crux of this for me, that these emails are kind of an abdication of responsibility. They are leapfrogging over (what I assume is) discomfort at actually dealing with people in favor of tasking the employee. Why have managers if they aren't responsible for the productivity of their underlings? Why make this an all-hands piece of information? It's passing the buck.
The two emails are two extremes of this: the first uses authority, the second uses information. "Tell us why we shouldn't hate you," vs. touchy-feely Lumbergh-ism. Both are too much. Tell the bosses of the people slacking off and let the employee's manager deal with it under pain of their job being at risk. Isn't that what a management hierarchy is for?
Fix the management problem and you largely fix the communication problem. For the rest (benefits changes, business strategy, etc), the exec whose name is at the bottom would be well served to be as transparent and honest as possible, and for sensitive topics to include formal feedback/Q&A paths to clarify any uncertainties. There is a huge perception gap between levels of employees and it's literally the case that individuals at different levels in the hierarchy (or different LOBs/divisions) have no idea how to relate to one another; what usually happens is that they freeze and avoid engagement, which only hurts the company.