I've done both. Generally I try to stop posting inflammatory emails until I've tried to understand the intended meaning but sometimes even carefully crafted emails can be misconstrued with the lack of a comma in the right place etc. I still prefer to speak face to face to ensure that what I mean to say comes through and that I understand fully the other parties intent.

I worked for a private bank a few years ago, with a very friendly close knit staff. A colleague sent an email out basically warning of an impending lack of service to the entire bank. One member of staff replied with a one word reply implying that he was born out of wedlock. It would have been funny to both parties and no harm done...but he hit reply to all instead of reply and didn't notice until the replies started flooding in. If this had been other sites I'd worked at there would have been fireworks, but luckily everyone viewed the incident as a joke.