Flame wars have a long and interesting history on the Internet.
It doesn't take much to get people started pushing each others buttons' when using email. Indeed, some see insults as an art form. Some have no compunction about destroying otherwise genteel conversation or sincere debate. I got into a debate on a list called cues-l. Cues-L was set up to discuss the use of nonverbal cues to increase the comfort level of students in email classes such as ours.