it's slander if spoken, libel if written. an e-mail is not a privileged communication, if any of the recent court cases are good precedent. however, there may be a reasonable expectation of privacy in regard to e-mails sent by "john smith" (if that's his real name) to his attorney, clients or doctor. hence it would be a breach of privacy if "john smith" released public information about the person who sold or purchased an item that was freely available elsewhere IMVHO. (I ain't a lawyer)