Is there a suitable substitute for tl;dr that you would find less distracting?

I recently had a need for such substitute to summarize a long email to an extremely busy non-chatty high-status person. I went with "In a nutshell", and it worked -- I got a nice reply.

(TL;DR is perfectly fine with me, but I don't think it's appropriate when addressing people who are unlikely to keep up with the latest Internet slang.)