A function called to save outgoing articles. This function will be
called with the name of the file to store the article in. The default
message-output which saves in Unix mailbox format.
When sending combined messages, this string is inserted at the start of
the mailed copy. If the string contains the format spec ‘%s’, the
newsgroups the article has been posted to will be inserted there. If
this variable is
nil, no such courtesy message will be added.
The default value is ‘"The following message is a courtesy copy of
an article\\nthat has been posted to %s as well.\\n\\n"’.
nil, attach files as normal parts in FCC copies; if it is
nil, attach local files as external parts.
nil wait for and display errors when sending a message;
nil let the mailer mail back a message to report errors.
nil, Gnus will ask for confirmation when sending a