Q:  What is top-posting?

A:  Top-posting is the practice of replying to an email and placing your
    text at the top of the reply, before all other text.



Q:  Why is top-posting evil?

A1: Because top-posters tend to leave the entirety of the email to which
    they are replying intact, so the email gets too long.

A2: Because we prefer to use bottom-posting, and it is *extremely* hard to
    maintain a coherently flowing email conversation when some of the
    participants are bottom-posting and some are top-posting.

A3: backwards read don't humans because



Q:  Why should I stop top-posting?

A1: Because then people are more likly to reply to your email

A2: Because top-posting makes you look clueless (sorry).



Q:  How do I bottom-post?

A:  Edit your interlocutor's email down to just the relevant parts to which
    you are replying and then place your reply beneath that.

    Added bonus!  You can intersperse your replies in between your
    interlocutor's text, enabling readers to more easily see the connection
    between your words and his.



Q:  Is it ever OK to top-post?

A:  Rarely.  Sometimes it makes sense if you are forwarding the entirety of
    an email to additional parties and you expect that those parties will be
    responding in the normal bottom-posting manner.