mimefilter - filter a MIME message stripping unwanted MIME parts

       The mimefilter script cheerfully takes an unlimited number of command line arguments and happily discards
       them all.

       This   program   has   been  written  and  is  actively  maintained  by  Davide Giovanni Maria  Salvetti,
       <salve@linux.it>.

       Naaa... ;-)

       The mimefilter script accept on STDIN a MIME conforming message, and outputs on STDOUT a MIME conforming
       message.

       It strips every unwanted MIME part, warning by email the original author about this, and outputs a MIME
       compliant cleaned message, to be further processed by a mailing list software.

       You may find it useful if you don't want certain attachments on your mailing lists, or if you want to
       allow just the text part from multipart/alternative messages, and so on.  You can easily fine tune the
       list of allowed MIME types to suit your particular needs, using normal Perl regexps.

       The mimefilter script will look for the following environment variables:

       list
           The name of the mailing list this message is intended for.  Used as the return address of the warning
           issued to the orginal author if the message is not already clean.

           The Smartlist mailing list software will automatically pass this variable to mimefilter.

       listaddr
           The address of the mailing list this message is inteded for.  Used in the X-Loop field of the warning
           issued to the original author if the message is not already clean.

           The Smartlist mailing list software will automatically pass this variable to mimefilter.

       listreq
           The administrative (owner) address of the mailing list this message is  inteded  for.   Used  in  the
           return address of the warning issued to the original author if the message is not already clean.

           The Smartlist mailing list software will automatically pass this variable to mimefilter.

       maintainer
           The  email  address  of  the  maintainer  of  the mailing list this message is inteded for.  If it is
           defined, it is used to send the maintainer original carbon copies of messages that have been modified
           by this filter -- if filter_mime_cc_maintainer is affermative, of course.

           The Smartlist mailing list software will automatically pass this variable to mimefilter.

       filter_mime_cc_maintainer
           A boolean flag: if affermative (i.e., if it matches the /y/i Perl regular expression), the mimefilter
           script will send carbon copies of every cleaned (modified) message to the maintainer of  the  mailing
           list the message is intended for.

           Users of the Smartlist mailing list software may conveniently set this variable in rc.custom.

       filter_mime
           The  mimefilter  script  itself will pay no attention to this variable, but if you have followed what
           the author suggests in the RECOMMENDED USE WITH THE SMARTLIST MAILING LIST SOFTWARE section, you will
           need to define it affermative in rc.custom to activate this script:

                   filter_mime = yes

       The  mimefilter  script  will  look for a system wide configuration file in /etc/mimefilter.rc, and for a
       local, per working directory, configuration file in ./mimefilter.rc.  The latter may be used to  override
       any or all of the parameters defined by the former, thus allowing easily per mailing list customization.

       Several configuration parameters are provided, the most important being the list of admissible MIME types
       (where  Perl  regexps may be used), along with the list of never to be allowed ones (so that you may even
       specify, e.g., 'text/.*'  in the admissible types list and 'text/html' in the never to be allowed one, to
       allow every text part but html ones).

       See the default configuration file for examples of use and further documentation.

       This script was originally aimed for use with a  bunch  of  Smartlist  served  maling  lists  the  author
       administers.  He believes it can be successfully used with other mailing list softwares as well.

Debian Project                                     2020-09-03                                      MIMEFILTER(1)

       mimefilter - filter a MIME message stripping unwanted MIME parts

       The mimefilter script may take just an option, in either its short or long form:

       -h, --help
           Causes the script to print this very manpage and then succesfully exit.

       However, the mimefilter script won't bark at you if it discovers you supplied some other options as well,
       it'll just politely ignore them.

       Put the following lines in rc.local.s[012]0 (the right one just depends on your specific needs,  look  at
       rc.submit for more info):

           :0
           * filter_mime ?? y
           {
                   # Pass the mail trough mimefilter
                   :0 fw
                   | mimefilter

                   # Executed if mimefilter died
                   :0 e
                   {
                           :0 hfw
                           | formail -A "X-Diagnostic: MIME filtering failed"

                           HOST=continue_with_rc.request
                   }

                   # Trash empty messages (author's already been warned by mimefilter)
                   :0 Bh
                   * < 1
                   /dev/null
           }

       Also  remember  to  uncomment  the appropriate line in rc.custom, to activate rc.local.s[012]0, and don't
       forget to customize the list of admissibile and never to be  allowed  MIME  types  in  the  configuration
       file(s).

       The mimefilter script returns 0 on success and a positive integer on errors.

       The Smartlist mailing list software documentation, the mimefilter.rc(5) man page (yet to be written).

       mimefilter [OPTIONS]

       This program is copylefted.  Refer to the GNU General Public License for conditions of use.

       The  author  believes  no  particular  arrangements  are  necessary  to use this script with mailing list
       software other than Smartlist, altough one should remember that mimefilter expects to find at  least  the
       list, listaddr, and listreq environment variables set.