Tim:
It's the same as following someone home then picking a fight with them, because you no-longer feel obliged to behave with decency. They only way to stop someone doing that sort of thing is to make it known what they're doing.
Ralf Corsepius:
Sometimes no, sometimes yes.
In most cases it's disclosing information or providing background information/opinions which are not appropriate/relevant for the public audience.
Certainly, I couldn't justify publicising someone's confidential information, but I can justify making it known that someone likes to send offensive messages when they think they can get away with it. For what it's worth, such offensive mail would contravene laws in some quarters, to begin with (offensive, threats, etc.).