Condo association board emails can be offensive - how to clean it up?

I serve as treasurer on our board and have for 4 years. The problem we face is long term board members whose email conduct is less than professional. The individual is terse and harsh towards any other board member who does not agree. Overall the board has worked hard to improve its image as being professional and non-confrontational to owners and minimize/eliminate the "good ole boy" operational concept. Please any thoughts from others who have faced this dilemma.