cancel <message ID>
If an article with the given message ID is present on the local system, the article is cancelled. This mechanism allows a user to cancel an article after the article has been distributed over the network.
Only the author of the article or the local super user is allowed to use this message. The verified sender of a message is the Sender line, or if no Sender line is present, the From line. The verified sender of the cancel message must be the same as either the Sender or From field of the original message. A verified sender in the cancel message is allowed to match an unverified From in the original message.