There are four styles for replying to an e-mail.
- Do not quote the original message
- Top Put your reply above the quoted text of the original message
- Bottom Put your reply below the quoted text of the original message
- Quote relevant parts of the original message with your reply following each quote
I agree with John Gruber (Daring Fireball) that the last is the preferred method.
But some of my friends—for some reason—do not keep an archive of their e-mail messages. They rely on people who respond to not only quote the previous message, but the entire thread. In “top” fashion.
So, I try to oblige.