Email piles up quickly and the saved messages must be thinned out from time to time. A good subject line helps immensely. Be informal . Email messages are more like little notes or memos than formal letters. Quote enough of a previous message to be sure that the reader knows what you are talking about.
Long files take a long time to load and read.
Your email program may automatically quote the whole message that you are replying to. Delete the parts that aren't needed to make your own message clear. Sarcasm is difficult to get across accurately. Limit your use of abbreviations since many won't understand what you mean. Here's your message.