I just thought of another reason I either delete or leave the original at the top...

Have you ever gotten an e-mail and thought it was nice and long and excitedly start reading...then discover over half of it is your original at the end??

I think that is why I either delete everything (no repeats), edit the mail I am responding to so it only has certain portions left - and then start my own message under it Mostly, I prefer to NOT leave any original in my e-mail.

Now PM's are usually short so I sometimes leave the original in them but yes, I start typing underneath I never really thought of much "e-mail" ettiquette