| Control messages are used for communication among USENET host machines, not to be read by users. Control messages are distributed by the
same newsgroup mechanism as ordinary messages. The body
of the Control header line is the message to the host.
For upward compatibility, messages that match the
newsgroup pattern "all.all.ctl" should also be
interpreted as control messages. If no Control: header is
present on such messages, the subject is used as the
control message.
- Standard for Interchange of USENET Messages; Mark Horton;
RFC 850; June 1983. |
You can cancel a Usenet message after you send it, but that doesn't guarantee
it won't get archived first.
You might sometimes post a message and then
wish to cancel it, either because the message contained incorrect information,
or because you regretted what you posted. Of course, the best recommended protection
against
this is to reread everything before you post it to the Internet and ask
yourself if you're sure you want to send it out to the entire world.
However, if
you do send a post and wish to cancel it, you can send another
post to the same newsgroup with a "control" header that specifies a "cancel"
command along with the <message-ID> on the message you want to cancel.
Most news
readers contain a built-in menu command to cancel a posting. For example,
on Netscape, highlight the article, and then select the menu item "Edit / Cancel"
which will display the following.
Control: cancel <message-ID>
The
cancel message will first be sent to your local news server, which will delete
the message from their server right away, and then send the command to all other
news servers to which it sent the message in the first place, so that it will
be removed at about the same speed that it was posted.
However, remember
that there is no guarantee that someone won't read your message before it is
canceled,
especially if the cancel is sent several minutes after the original message.
Also, there is no guarantee that it will be canceled before some newsgroup
archive picks
it up and stores it in their database.
