I've been contemplating the Buddhist concept of right speech for about a year now. The seeds go even deeper, to hearing Rachel speak of an enlightened time when she could think no evil towards others, and later to noticing that Benny rarely ever said bad things to say about anyone or anything. Everyone teaches us something, isn't that beautiful?
Anyways, so yes, what is "right speech?" Well, one source I liked said, "Abstaining from lying, abstaining from divisive speech, abstaining from abusive speech, abstaining from idle chatter." Pretty simple. The ones I've been reminded of lately are gossiping and back-biting. Poisoning other's perceptions of people in other words. It's all irrevocably tied into "right thought," another Buddhist principal. I think Jesus summed it all up pretty well with, "Love one another." Most words, thoughts, or deeds either bring you closer to or farther away from love.
So one caveat I would like to add to the wisdom that has come before. More of a safeguard than anything: Never try to solve a dispute through online communication, specifically email. Humans can't get their emotions across correctly, and its so much easier to be concerned about your own feelings when you see a field of text instead of a person. Such selfishness isn't love. Maybe future, more internet savvy generations will evolve to get around this space that the internet provides, but until then, that's my advice. When I have talked things out with someone face to face, it has always been good.