The message-cancel-news command cancels the article in the
current buffer.
The value of message-cancel-message is inserted in the body of
the cancel message. The default is ‘I am canceling my own
article.’.
When Message posts news messages, it inserts Cancel-Lock
headers by default. This is a cryptographic header that ensures that
only you can cancel your own messages, which is nice. The downside
is that if you lose your .emacs file (which is where Gnus
stores the secret cancel lock password (which is generated
automatically the first time you use this feature)), you won’t be
able to cancel your message. If you want to manage a password yourself,
you can put something like the following in your ~/.gnus.el file:
(setq canlock-password "geheimnis"
canlock-password-for-verify canlock-password)
Whether to insert the header or not is controlled by the
message-insert-canlock variable.
Not many news servers respect the Cancel-Lock header yet, but
this is expected to change in the future.