I recently wrote about closing emails and noted that “Yours truly” is stilted and somewhat archaic. When you think about what those words mean, you see how silly they are when taken literally. (However, I guess that is a better closing than when people regularly closed their letters with “Your Obedient Servant.”)
Similarly, when we begin an email with the salutation “Dear,” perhaps we should think about how many of the recipients of our emails are truly “dear” to us. When writing casually, starting with “Hello,” “Good morning” or “Hi” can all be acceptable, given your relationship with the person or people you’re writing to. In a more formal situation or when writing to someone in a higher position, you can begin your email like this:
To Ms. Jane Doe: or To the Director of Human Relations (if you cannot discover that person’s name): Then begin your message.
When writing more formally, use a colon after the greeting. After a more casual greeting, a comma is fine.