When I worked for Apple Computer, I would get hundreds of emails a day. It was a challenge to get through them. Of the course of twenty years I am sure a few fell through the cracks, but mostly I was able to keep up with them.
I never succumbed to the read the first line and call it quits method of email management. I did answer many questions from people who had not bothered to the read the whole email in the first place.
Depending on how I felt at a given time, I might copy and paste the originial email with the answers highlighted. However, I did find that the worst offenders never noticed.
Lately I have seen an even more serious email management disease. These folks read the title of an email and assume they know what it says.
That is not only highly risky but certainly not very productive. A couple of responses that I have gotten from people trying this are beyond worthless.
I guess it is function of the desire to get ever more done with little focus on actually be productive.
I would rather do less and make certain that I get right whatever I do.