Variable: nnmail-treat-duplicates

nnmail-treat-duplicates is a customizable variable defined in nnmail.el.gz.

Value

warn

Documentation

If non-nil, nnmail keep a cache of Message-IDs to discover mail duplicates.

Three values are valid: nil, which means that nnmail is not to keep a Message-ID cache; warn, which means that nnmail should insert extra headers to warn the user about the duplication (this is the default); and delete, which means that nnmail will delete duplicated mails.

This variable can also be a function. It will be called from a buffer narrowed to the article in question with the Message-ID as a parameter. It should return nil, warn or delete.

Probably introduced at or before Emacs version 19.32.

Source Code

;; Defined in /usr/src/emacs/lisp/gnus/nnmail.el.gz
(defcustom nnmail-treat-duplicates 'warn
  "If non-nil, nnmail keep a cache of Message-IDs to discover mail duplicates.
Three values are valid: nil, which means that nnmail is not to keep a
Message-ID cache; `warn', which means that nnmail should insert extra
headers to warn the user about the duplication (this is the default);
and `delete', which means that nnmail will delete duplicated mails.

This variable can also be a function.  It will be called from a buffer
narrowed to the article in question with the Message-ID as a
parameter.  It should return nil, `warn' or `delete'."
  :group 'nnmail-duplicate
  :type '(choice (const :tag "off" nil)
		 (const warn)
		 (const delete)))