Hey, Folks: Here's a Digital Requiem for a Dearly Departed Salutation - WSJ.com →
Here is my etiquette (after a brief analysis today):
(1) For friends & family, it is a “Hi” or no-salutation at all. Also, it could be a “Dei”, “Machan/Machi/Maapla”, “Bhailog”, “Dost”, “Kher” etc as the case may be… (and some unintelligible gibberish in the name of being romantic, if the recipient happens to be my wife)
(2) Within office, “Hi” if the person is known well enough and is not very senior to me. For unfamiliar & very senior people, it is a “Hello”
(3) For business partners, “Hello” usually but if it is a reply, I use what they have used, including “Dear” (though as the article says, that person could be the undearest person to me ever!) :)
Peace!