It's a CYA world - you have to write that long email, I get it. So go ahead and do that, but then do something nobody is expecting you to do.
Think about it - you hate long emails and read about 10% of the total words that are sent to you. Most of you have already spaced out a bit on this post. So use a summary that just happens to engage via the trendy state of Twitter to make you look more hip and up to date than you really are.
For example, if I were summarizing this post in twitter form, I'd break something off like this:
"From @kris_dunn: You're ignoring my long emails and trying to fake it. I can take a hint, from now on I'm breaking it down in 140 spaces. #you'rewelcome"
I recently used a twitter summary as a header for a full position description on for a VP of HR role I filled and got excellent response:
"@EPIUSEAmerica seeks human capital sage. Big brain, no ego, builder of teams. Tech biz, whiteboard the talent future for one of the best."
Finally, here's the twitter summary of a longer description for a presentation I'm doing this fall called "The 9 Faces of HR":
"Every HR pro in the world is one of The 9 Faces of HR. Join us at <insert conference> as keynote @kris_dunn covers the 9 Faces and tells us which one YOU are."
My take is that the twitter format is better than the text message format for a couple of reasons - first up, the @ handles let you address the people you're talking to, which is good and interest driving, and hashtags let you add some humor and context as well.
Play around with it. Great way to stand out from the crowd in your company - which is undoubtedly filled with too many long emails.