Dear Mark, how are you?
I get this message quite frequently. The trouble is that all it creates in me is the feeling that person wants something but first they are dressing it up with small talk. To be honest, it's not the way to go about it. Because everyone knows that you are leading to something. Which makes the request about my well-being to be considered not-entirely-genuine.
Dear Mark, I'm looking for somewhere to rehearse my new play. Hey Mark, could I get your advice on something?
This gets to the point. It doesn't dress it up as a nice chat, it bottom lines the favour that's required. THEN when you ask how I am after that, I know because you are genuinely interested, because you have got the REAL reason for the message out of the way.
If you are contacting someone, be honest with them first, you will appear more genuine and it will not result in the person distrusting your motives.
No one is taken in with 'how are you?' - get to the point.
To You, The Best