Because an email allows me to field it when I am not working on high-focus tasks. It also 1) forces (or at least encourages) laying the whole thing out in a c

Because an email allows me to field it when I am not working on high-focus tasks. It also 1) forces (or at least encourages) laying the whole thing out in a coherent order 2) leaves a record of both the question and the answer, so that the asker can refer back to it if they forget 3) leaves a record so that if the asker is asking obvious questions, or repeatedly asking the same questions, or failing to formulate their questions in a sane and coherent manner, there is documentation to take to their supervisor, not only to prove it, but to show exactly the shape of the problem, and have a possibility of getting them the kind of help they need