As a design community we email poorly - way too many words, not enough pictures/sketches/details/screen shots.   It is still the coordination tool of choice today, but there isn't one way to email.  Add lots of screen shots! Here is a bad email...

"Erik,  On grid line 8 east of wall A, near the dining room wall, there is a post that needs to be moved 6" to the north.   Remember, north is to the left on the PDF set you have.  Sincerely, Bobby Cantemail"

Here is a good email...