2 greetings
Formal or neutralizing: usually begins with a study guide Dear Mr., Mrs., Ms + people like Dear Mr. Sun, Dear K.Naree if not by name, use Dear Sir / Madam, if sent to multiple users simultaneously. they use Dear All, Dear Colleague, Informal: say hello like a Hi / Hello to the name or not to name it as Dear or Dear Mary, or to put a name to make it here as Mary,.