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Gnus Manual

6.3.6 Fancy Mail Splitting

If the rather simple, standard method for specifying how to split mail doesn't allow you to do what you want, you can set nnmail-split-methods to nnmail-split-fancy. Then you can play with the nnmail-split-fancy variable.

Let's look at an example value of this variable first:

;; Messages from the mailer daemon are not crossposted to any of ;; the ordinary groups. Warnings are put in a separate group ;; from real errors. (| ("from" mail (| ("subject" "warn.*" "mail.warning") "mail.misc")) ;; Non-error messages are crossposted to all relevant ;; groups, but we don't crosspost between the group for the ;; (ding) list and the group for other (ding) related mail. (& (| (any "ding@ifi\\.uio\\.no" "ding.list") ("subject" "ding" "ding.misc")) ;; Other mailing lists... (any "procmail@informatik\\.rwth-aachen\\.de" "procmail.list") (any "SmartList@informatik\\.rwth-aachen\\.de" "SmartList.list") ;; Both lists below have the same suffix, so prevent ;; cross-posting to mkpkg.list of messages posted only to ;; the bugs- list, but allow cross-posting when the ;; message was really cross-posted. (any "bugs-mypackage@somewhere" "mypkg.bugs") (any "mypackage@somewhere\" - "bugs-mypackage" "mypkg.list") ;; People... (any "larsi@ifi\\.uio\\.no" "people.Lars_Magne_Ingebrigtsen")) ;; Unmatched mail goes to the catch all group. "misc.misc")

This variable has the format of a split. A split is a (possibly) recursive structure where each split may contain other splits. Here are the five possible split syntaxes:

1. `group': If the split is a string, that will be taken as a group name. Normal regexp match expansion will be done. See below for examples.

2. (field value [- restrict [...]] split): If the split is a list, the first element of which is a string, then store the message as specified by split, if header field (a regexp) contains value (also a regexp). If restrict (yet another regexp) matches some string after field and before the end of the matched value, the split is ignored. If none of the restrict clauses match, split is processed.

3. (| split...): If the split is a list, and the first element is | (vertical bar), then process each split until one of them matches. A split is said to match if it will cause the mail message to be stored in one or more groups.

4. (& split...): If the split is a list, and the first element is &, then process all splits in the list.

5. junk: If the split is the symbol junk, then don't save this message. Use with extreme caution.

6. (: function arg1 arg2 ...): If the split is a list, and the first element is :, then the second element will be called as a function with args given as arguments. The function should return a split.

   For instance, the following function could be used to split based on the body of the messages:

   (defun split-on-body () (save-excursion (set-buffer " *nnmail incoming*") (goto-char (point-min)) (when (re-search-forward "Some.*string" nil t) "string.group")))

7. (! func split): If the split is a list, and the first element is !, then SPLIT will be processed, and FUNC will be called as a function with the result of SPLIT as argument. FUNC should return a split.

8. nil: If the split is nil, it is ignored.

In these splits, field must match a complete field name. value must match a complete word according to the fundamental mode syntax table. You can use .* in the regexps to match partial field names or words. In other words, all value's are wrapped in `\<' and `\>' pairs.

field and value can also be lisp symbols, in that case they are expanded as specified by the variable nnmail-split-abbrev-alist. This is an alist of cons cells, where the car of a cell contains the key, and the cdr contains the associated value.

nnmail-split-fancy-syntax-table is the syntax table in effect when all this splitting is performed.

If you want to have Gnus create groups dynamically based on some information in the headers (i.e., do replace-match-like substitutions in the group names), you can say things like:

(any "debian-\\b\\(\\w+\\)@lists.debian.org" "mail.debian.\\1")

In this example, messages sent to `debian-foo@lists.debian.org' will be filed in `mail.debian.foo'.

If the string contains the element `\&', then the previously matched string will be substituted. Similarly, the elements `\\1' up to `\\9' will be substituted with the text matched by the groupings 1 through 9.

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 nnmail-treat-duplicates to a non-nil value. And then you can include nnmail-split-fancy-with-parent using the colon feature, like so:

(setq nnmail-split-fancy '(| (: nnmail-split-fancy-with-parent) ;; other splits go here ))

This feature works as follows: when nnmail-treat-duplicates is non-nil, Gnus records the message id of every message it sees in the file specified by the variable 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 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 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 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.) When nnmail-cache-accepted-message-ids is non-nil, Gnus also records the message ids of moved articles, so that the followup messages goes into the new group.