The only advantage of top posting I can think of is that it enables you to forward the entire chain of emails to a new person with one click. You could, of course, bottom post and keep the entire chain in each email, but it's probably even worse than top posting, since you would have to scroll through the whole mess each time just to see what another person said. So in office environment, top posting is probably preferable to bottom posting. Although I do switch to bottom posting even when replying to office-style communication when I get a big list of unrelated questions. Bottom posting shows its downside only when you recently joined a mailing list, for example - you start receiving emails from threads that have been going for a long time and you have no idea what people are discussing. But if you're really interested, you can always use the archive. Denis.
