Variable: nnmail-cache-accepted-message-ids
nnmail-cache-accepted-message-ids is a customizable variable defined
in nnmail.el.gz.
Value
nil
Documentation
If non-nil, put Message-IDs of Gcc'd articles into the duplicate cache.
If non-nil, also update the cache when copy or move articles.
Source Code
;; Defined in /usr/src/emacs/lisp/gnus/nnmail.el.gz
(defcustom nnmail-cache-accepted-message-ids nil
"If non-nil, put Message-IDs of Gcc'd articles into the duplicate cache.
If non-nil, also update the cache when copy or move articles."
:group 'nnmail
:type 'boolean)