As a bonus, it will seem that your superior intellect is cutting through all the excess verbiage to the very heart of the matter. Points are awarded for getting the last word in. Drawing the conversation out so long that the original message disappears due to being indented off the right hand edge of the screen is one way to do this. Another is to imply that anyone replying further is a hopeless cretin and is wasting everyone's valuable time. Users should cultivate an ability to make the simplest molehill into a mountain by finding controversial interpretations of innocuous sounding statements that the sender never intended or imagined.
Electronic mail is an indispensible component of the automated office.
Besides providing entertainment, it gives one the appearance of engaging in industrious and technically sophisticated activity. Trivialize a user's bug report by pointing out that it was fixed independently long ago in a system that hasn't been released yet.