Have you ever written something, and then decided that you really, really, really wish you hadn’t posted that?
Well, you can’t cancel mail, but you can cancel posts.
Find the article you wish to cancel (you can only cancel your own
articles, so don’t try any funny stuff). Then press C or S
c (gnus-summary-cancel-article). Your article will be
canceled—machines all over the world will be deleting your article.
This command uses the process/prefix convention (see Process/Prefix).
Be aware, however, that not all sites honor cancels, so your article may live on here and there, while most sites will delete the article in question.
Gnus will use the “current” select method when canceling. If you want to use the standard posting method, use the ‘a’ symbolic prefix (see Symbolic Prefixes).
Gnus ensures that only you can cancel your own messages using a
Cancel-Lock header (see Canceling News in Message Manual).
If you discover that you have made some mistakes and want to do some corrections, you can post a superseding article that will replace your original article.
Go to the original article and press S s
(gnus-summary-supersede-article). You will be put in a buffer
where you can edit the article all you want before sending it off the
usual way.
The same goes for superseding as for canceling, only more so: Some sites do not honor superseding. On those sites, it will appear that you have posted almost the same article twice.
If you have just posted the article, and change your mind right away,
there is a trick you can use to cancel/supersede the article without
waiting for the article to appear on your site first. You simply return
to the post buffer (which is called *sent ...*). There you will
find the article you just posted, with all the headers intact. Change
the Message-ID header to a Cancel or Supersedes
header by substituting one of those words for the word
Message-ID. Then just press C-c C-c to send the article as
you would do normally. The previous article will be
canceled/superseded.
Just remember, kids: There is no ’c’ in ’supersede’.