Direct. No salutation, no contact info. Bottom line up front. Short: 4 paragraphs of 4 sentences is an upper bound, one to two sentences preferred. Actionable. No story, no background. NO ATTACHMENTS unless you are specifically sending them something they asked for. BEAM INFORMATION INTO YOUR HEAD.
A high S/high C would call the same email too short, underspecified and cold/angry.
You've got a huge corpus to train from, read your boss's emails and reply using her style. Improves communication (ie, the actual ability to get your thought into their head) and appreciation.
See also Email and the High I. Looking forward to "Email and the High C" and "Email and the High S," I hope they get recorded and shared.