once you send a message to another person it is legally their property. that it. you no longer have any rights over. courtesy might suggest you keep it to yourself but there is no obligation, especially if the message was threatening defamatory or otherwise illegal. to expect anything else is dumb like a post.
everything you post on the internet is savd somewhere, and can be used publiccly and if you don't like it, stop posting.
i usually save my serious insulkts for the open discussions, but that is because i am hostle to racism and i am disgusted by the amount of open or thinly vieled racism on mudcat.
that's why i don't post much anymore, the discussions are rarely worthwhile.
however all personal messages become the property of the recipient when they are recieved and to think otherwise is dumb