+@findex nnmail-split-fancy-with-parent
+@code{nnmail-split-fancy-with-parent} is a function which allows you to
+split followups into the same groups their parents are in. Sometimes
+you can't make splitting rules for all your mail. For example, your
+boss might send you personal mail regarding different projects you are
+working on, and as you can't tell your boss to put a distinguishing
+string into the subject line, you have to resort to manually moving the
+messages into the right group. With this function, you only have to do
+it once per thread.
+
+To use this feature, you have to set @code{nnmail-treat-duplicates} to a
+non-nil value. And then you can include
+@code{nnmail-split-fancy-with-parent} using the colon feature, like so:
+@lisp
+(setq nnmail-split-fancy
+ '(| (: nnmail-split-fancy-with-parent)
+ ;; other splits go here
+ ))
+@end lisp
+
+This feature works as follows: when @code{nnmail-treat-duplicates} is
+non-nil, Gnus records the message id of every message it sees in the
+file specified by the variable @code{nnmail-message-id-cache-file},
+together with the group it is in (the group is omitted for non-mail
+messages). When mail splitting is invoked, the function
+@code{nnmail-split-fancy-with-parent} then looks at the References (and
+In-Reply-To) header of each message to split and searches the file
+specified by @code{nnmail-message-id-cache-file} for the message ids.
+When it has found a parent, it returns the corresponding group name. It
+is recommended that you set @code{nnmail-message-id-cache-length} to a
+somewhat higher number than the default so that the message ids are
+still in the cache. (A value of 5000 appears to create a file some 300
+kBytes in size.)
+@vindex nnmail-cache-accepted-message-ids
+When @code{nnmail-cache-accepted-message-ids} is non-@code{nil}, Gnus
+also records the message ids of moved articles, so that the followup
+messages goes into the new group.
+
projects / gnus / blobdiff