I think your comment depends entirely upon your default style of writing. For me its usually the opposite - I need to pad out my emails and clarify what I mean

I think your comment depends entirely upon your default style of writing. For me its usually the opposite - I need to pad out my emails and clarify what I mean when I say certain things. If I am working on a problem I have lots of concept in my head, and its my initial instinct to just write what I am thinking. On reading through the email a second time, I realize that I need to clarify what I mean by certain words / phrases as the reader hasn't been working on the same thing as me for the last few hours / days so their context will be very different from mine.