No. The whole point of these boards is to share information with others so that all can benefit.
Channelling the exchange of information into emails means that the people with the answers have to spend more time responding to the same enquiry over and over again. Many of these enquiries are not particularly sensitive and have no reason to be made in private.
And if everyone can see the question, the chances are that it'll be seen more quickly by someone who's in a position to answer.
So it saves time all round if questions are put on the board in the first place for all to see.
Please also see the FAQ about sending private messages.