I'm a huge a-hole, as you know, so I'll cut straight in saying "Blah. Get to the point."
Usually this just happens at work in which case I'll smile and nod and then when they look away I'll take off down the hallway or start talking to someone else. Short attention span cannot handle unnecessary detail. Email should be no more than 3 sentences.
"Create like a god, command like a king, work like a slave."