In the specific case of the opening salutation I would not insert a comma between the greeting and the name if a comma came after the name, but I would if some other punctuation followed the name.
The following examples all "look correct" to me:
"Hi Mark, how are you?"
"Hi, Mark. How are you?"
"Hello Mark, what's up?"
"Hello, Mark! What's up?"
But the "Hi, Mark, how have you been?" example that you gave looks over-punctuated to me.