Not yet a professor (am postdoc, hopefully get a position in next few years), but I view answering questions from the public as part of the job (learning something and not sharing the knowledge is worthless from a societal perspective). I tend to get a few emails from the public after a newspaper article or something comes out about me or my work, and i try to answer them if I think the question is serious. (I have gotten a few trying to sell me stuff, I ignore those).
I’m currently talking to someone about protecting windmills against lightning. This person has gotten advice from their lightning protection company they don’t really like and so has reached out to me. Unfortunately in this case I’m not able to be really helpful as I know very little about lightning protection, and I don’t want to be liable if he takes my advice and a windmill gets burnt down because of it.
I guess this is an aspect that the public may not see clearly, is that something you think may be part of the prof’s expertise may actually not be. (e.g. I study lightning, but I know nothing about weather and little about lightning protection). Another aspect is that academics move around a lot. The email adress you have may no longer be valid.