Liz Danzico:

When you email busy people, you might believe the best option you can give them is to offer a wide set of options (“I’m available any time in fall 2010. Choose a day that works for you!”) You imagine you’re being generous. Accommodating. You’re not imposing on the busy person.Yet what you’ve done, in one fell sentence, is impose more busy work on an already busy person.

True.