There is a certain set of people who email you back and always have their preferences set to not include any previous email history of the conversation. This makes it very frustrating to communicate with them for a few reasons:

a. They can email you back a week later, and at this point you have no clue what they are talking about. If you are such a person - I am sorry, I have a busy schedule, I don’t even attempt to remember everything. Even if I could remember it all, why do you you think your email and content is the one I would choose to remember? 

b. Even if they reply right back and you do know what the conversation is about, often you need to refer to details discussed previously in the conversation. It could be URLs, numbers, ideas, phone numbers. If the person suddenly clears the slate, you have to go out of your way into YOUR message history just to fetch it. At this stage you get pissed off that the other person is inconsiderate and is wasting your time when you could have just scrolled down.  This gets worse as the person continues to clear the history on every email they reply back.

c. It shows the person is possibly not organized himself, so you start to question their ability on some imaginary scale.

d. Last and not least, there are those who don’t clear the message history but instead change the Subject name of the email (or forum private message). While not as bad as clearing the history, this also makes for frustration as you need to THINK about what is coming in, rather than instantly recognizing it. I have to spot these among a lot of spam emails, it doesn’t help that each time the subject title changes even if the conversation topic does not.

So do the world a favor, just hit Reply and make sure your email settings don’t start a fresh new message from scratch all the time