In the last several years, it seems that the conventional greeting “Dear” has become stigmatized, and so emails now begin, “Hey Josh,” “Hi Josh,” “Hey there,” “Hey,” “Hi ya Josh,” and so forth.
Really, though, we should all use “Dear.” Unless you’re in fourth grade, “Dear So-and-So” isn’t a sign you’re in love. It is fitting when speaking to a man or a woman, young or old. “Dear” isn’t meaningless. It’s fond, formal, dignified.