Informality..or Irreverence?

I receive quite a few emails from students. There is quite a variety in the construction of those emails. In the U.S. some students write politely, and address me as Prof. Gopal or a variant thereof. A nice thank you is also included. On the other hand, quite a few omit any salutation, and just ask a question. So far I have not had the experience of "chat"ting with students here. Apparently Email etiquette is not part of the basic writing course that students take.

Students in the MBA program in Delhi, where I spent a few weeks this summer, communicate with me often, but always address me as Sir- whether it is in an email or while 'Chat'ting or SMS'ing me. One should not be surprised that, on the margin, employers would hire workers from abroad- they are more respectful, and this can extend to customer relationships too.