Gnus Manual. Node: Fancy Mail Splitting

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6.3.4: 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")
   ;; 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")
      ;; People...
      (any "larsi@ifi\\.uio\\.no" "people.Lars_Magne_Ingebrigtsen"))
   ;; Unmatched mail goes to the catch all group.

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 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).
  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.
  7. 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+\\)" "mail.debian.\\1")

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.

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