Learn some manners

I admit I haven't had to do much correspondence in an "offical" manner throughout my life, especially in English. However, I have noticed a universal trend ... that is addressing an email without a greeting.

This really gets to me, how hard can it be to greet the person reading your email? I noticed it first with an emeritus professor in our department who supervised one of my projects. I was like OK fine the guy has probably been teaching my current lecturers (yes he's that old) so I'll let it pass.
Then it was some of the HR people I had to deal with in my search for employment... hmm OK I am not going to work for your stupid company anyway.
AND THEN it was one of my bloody classmates, aggggghhh

I am not sure if there is some rule or such on this but I'll tell you this.. next time I get an email like that I am going to do what I usually do when someone doesn't greet me in real life:

Ali *mucking around on the computer, pretending to be doing uni work*
B: Do you know where is C? I need to talk to him.
Ali: Ooohh Hello B, how are you? I am gooood thanks I hope you're doing well too *a minute or two of greeing him*.... no I don't know where is C