Clarity, not vocabulary, is what makes professional writing effective across regional and international teams.
Professional writing is judged on how quickly the reader can act, not on how advanced the vocabulary is.
Lead with the request or the decision. Supporting detail belongs underneath it, not before it.
Keep sentences short enough to read once. If a sentence needs a second reading, split it.
Match tone to relationship. Over-formality can read as distance; over-familiarity can read as carelessness.