Choosing salutation phrases, or closing ones for that matter, can be tricky with changing times. While the latter is relatively simpler which just requires bit understanding in knowing the differences, the former can raise several questions to the mind. Is it alright? Does it sound respectable or not? Too formal/informal than required?
Moreover, today social media and other forms of instant communication getting over e-mails, which in turn took over ‘real’ letters, it adds more to the tension. While adding “Dear…” is usually the first and safest strategy, it might always be the best one or even required. In my case, I know the world is too complicated for a single strategy. It depends who I’m writing to.