If I email you a list of three questions... please don't email me back with a response that only answers the first one.
That does two things for me; one, it makes me think you are too busy to read the entire email thus leads me to question your thoroughness and if I should be doing business with you in the first place...
and two, it forces me to spend additional time and email you back the SECOND two questions, again, hoping for a response to both this time.
Please stop doing that. Thank you!