Email: Civility breakdown in the marketplace of ideas [MG]

It has been known for decades that it is common for emails to devolve into "flame wars," ostensibly because the respondents are not facing each other in person, so the impediments to civil behavior are lessened. However, everyone is on a learning curve, so those who are new to email (esp. when they are socially or emotionally immature in some way) fall into this pattern until they learn better self-restraint. It is hard for those of us with decades of experience in email though: With particularly obnoxious respondents, I have instituted a rule of two exchanges (statements and rebuttals) and then dropping the subject, forcefully if necessary. Of course, no one is making us hit the Reply button but our own itchy fingers...