gnus: Diary Headers Generation

 
 6.8.2.3 Diary Headers Generation
 ................................
 
 ‘gnus-diary’ provides a function called ‘gnus-diary-check-message’ to
 help you handle the ‘X-Diary-*’ headers.  This function ensures that the
 current message contains all the required diary headers, and prompts you
 for values or corrections if needed.
 
    This function is hooked into the ‘nndiary’ back end, so that moving
 or copying an article to a diary group will trigger it automatically.
 It is also bound to ‘C-c C-f d’ in ‘message-mode’ and
 ‘article-edit-mode’ in order to ease the process of converting a usual
 mail to a diary one.
 
    This function takes a prefix argument which will force prompting of
 all diary headers, regardless of their presence or validity.  That way,
 you can very easily reschedule an already valid diary message, for
 instance.