For many years, I've been railing against "top posting" -- creating e-mail (or similar) messages with quoted material from the previous messages (usually, the entire message, unabridged) in the thread at the bottom, and the added content at the top of the message. I just stumbled across this perfect little illustration of why it's a horrid practice:
A: Yes.
> Q: Are you sure?
>> A: Because it reverses the logical flow of conversation
>>> Q: Why is top posting annoying in email?
Dan's Mail Format Site has more on the evils of top posting -- and, more importantly, how to do it right with interleaving and bottom-posting.