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9.16.3 SpamAssassin, Vipul's Razor, DCC, etc

The days where the hints in the previous section were sufficient in avoiding spam are coming to an end. There are many tools out there that claim to reduce the amount of spam you get. This section could easily become outdated fast, as new products replace old, but fortunately most of these tools seem to have similar interfaces. Even though this section will use SpamAssassin as an example, it should be easy to adapt it to most other tools.

Note that this section does not involve the spam.el package, which is discussed in the next section. If you don't care for all the features of spam.el, you can make do with these simple recipes.

If the tool you are using is not installed on the mail server, you need to invoke it yourself. Ideas on how to use the :postscript mail source parameter (see Mail Source Specifiers) follow.

     (setq mail-sources
           '((file :prescript "formail -bs spamassassin < /var/mail/%u")
             (pop :user "jrl"
                  :server "pophost"
                  :postscript
                  "mv %t /tmp/foo; formail -bs spamc < /tmp/foo > %t")))

Once you manage to process your incoming spool somehow, thus making the mail contain, e.g., a header indicating it is spam, you are ready to filter it out. Using normal split methods (see Splitting Mail):

     (setq nnmail-split-methods '(("spam"  "^X-Spam-Flag: YES")
                                  ...))

Or using fancy split methods (see Fancy Mail Splitting):

     (setq nnmail-split-methods 'nnmail-split-fancy
           nnmail-split-fancy '(| ("X-Spam-Flag" "YES" "spam")
                                  ...))

Some people might not like the idea of piping the mail through various programs using a :prescript (if some program is buggy, you might lose all mail). If you are one of them, another solution is to call the external tools during splitting. Example fancy split method:

     (setq nnmail-split-fancy '(| (: kevin-spamassassin)
                                  ...))
     (defun kevin-spamassassin ()
       (save-excursion
         (save-restriction
           (widen)
           (if (eq 1 (call-process-region (point-min) (point-max)
                                          "spamc" nil nil nil "-c"))
               "spam"))))

Note that with the nnimap back end, message bodies will not be downloaded by default. You need to set nnimap-split-download-body to t to do that (see Client-Side IMAP Splitting).

That is about it. As some spam is likely to get through anyway, you might want to have a nifty function to call when you happen to read spam. And here is the nifty function:

     (defun my-gnus-raze-spam ()
       "Submit SPAM to Vipul's Razor, then mark it as expirable."
       (interactive)
       (gnus-summary-save-in-pipe "razor-report -f -d" t)
       (gnus-summary-mark-as-expirable 1))