notmuch --config:alt-config config get user.name
notmuch --config alt-config config get user.name
+.. _duplicate-files:
+
+DUPLICATE MESSAGE FILES
+=======================
+
+Notmuch considers the :mailheader:`Message-ID` to be the primary
+identifier of message. Per :rfc:`5322` the :mailheader:`Message-ID` is
+supposed to be globally unique, but this fails in two distinct
+ways. When you receive copies of a message via a mechanism like
+:mailheader:`Cc` or via a mailing list, the copies are typically
+interchangeable. In the case of some broken mail sending software, the
+same :mailheader:`Message-ID` is used for completely unrelated
+messages. The options :option:`search --duplicate` and :option:`show
+--duplicate` options provide the user with control over which message
+file is displayed. Front ends will need to provide their own
+interface, see e.g. the Emacs front-end :any:`emacs-show-duplicates`.
+
ENVIRONMENT
===========
``c ?``
Show all available copying commands
+.. _emacs-show-duplicates:
+
+Dealing with duplicates
+-----------------------
+
+If there are are multiple files with the same :mailheader:`Message-ID`
+(see :any:`duplicate-files`), then :any:`notmuch-show` displays the
+number of duplicates and identifies the current duplicate. In the
+following example duplicate 3 of 5 is displayed.
+
+.. code-block::
+ :emphasize-lines: 1
+
+ M. Mustermann <max@example.com> (Sat, 30 Jul 2022 10:33:10 -0300) (inbox signed) 3/5
+ Subject: Re: Multiple files per message in emacs
+ To: notmuch@notmuchmail.org
+
+To display a different message file with the same
+:mailheader:`Message-ID`, the user can run the command
+:emacscmd:`notmuch-show-choose-duplicate`, by default bound to `%`.
+
+.. emacscmd:: notmuch-show-choose-duplicate
+
+ |docstring::notmuch-show-choose-duplicate|
+
.. _notmuch-tree:
notmuch-tree