Randy Dean recommends attaching complex information as a document instead of putting it in the email body. Keep the message short and explicitly ask the recipient to slow down and review carefully, so they don't skim over important details in a crowded inbox.
Chapters
Hey everybody, here's a really quick email etiquette tip as part of my email etiquette video series. If you're thinking about sending something that may be a bit tricky or complicated by email, here's my strong recommendation: don't send all of that information in the actual email, but instead make it an attachment, maybe in Word or PDF or PowerPoint. Or Google Docs, put that attachment on the email, and then make your email say, hey everybody, this is a little tricky or complicated. Please take your time and review it carefully and let me know if you have any questions. Thus, that makes the email itself short, but the detailed information is attached, and that will tend to slow people down, especially those that are getting way too many emails and tend to gloss things over. Try that, see if it helps.