If a message with the given Message-ID is present on the local system, the message is cancelled. This mechanism allows a user to cancel a message after the message has been distributed over the network.
If the system is unable to cancel the message as requested, it should not forward the cancellation request to its neighbor systems.
Only the author of the message or the local news administrator is allowed to send 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.
RFC1036: [Source:"RFC-1036"] [Last Changed:December 1987] [Copyright: 1987 M. Horton, R. Adams]
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Up to RFC1036 3. Control Messages
Optional Header Lines: RFC1036 2.2.6. Control