Why send an email? Say it with Notes!
I think this is a very underutilized tool in Photoshop. You have the option to place sticky notes in an image with the Notes tool (N). When you double-click on the note, it opens up to reveal any content. This allows you to give people direction and be very specific about it, instead of saying ¬Change the section to the right of the image above the head near the left 1/3 of the section of the eyebrow.® Put a note on it, and you’re done.