Content filtering works like this: when a message is received by the list and you have enabled content filtering, the individual attachments are first compared to the filter types. If the attachment type matches an entry in the filter types, it is discarded.
Then, if there are pass types defined, any attachment type that does not match a pass type is also discarded. If there are no pass types defined, this check is skipped.
After this initial filtering, any multipart attachments that are empty are removed. If the outer message is left empty after this filtering, then the whole message is discarded. Then, each multipart/alternative section will be replaced by just the first alternative that is non-empty after filtering.
Finally, any text/html parts that are left in the message may be converted to text/plain if convert_html_to_plaintext is enabled and the site is configured to allow these conversions.s filter_contents Nos Yesi s_ Should Mailman filter the content of list traffic according to the settings below?s filter_mime_typesi sJ Remove message attachments that have a matching content type.s Use this option to remove each message attachment that matches one of these content types. Each line should contain a string naming a MIME type/subtype, e.g. image/gif. Leave off the subtype to remove all parts with a matching major content type, e.g. image.
Blank lines are ignored.
See also pass_mime_types for a content type whitelist.s pass_mime_typess Remove message attachments that don't have a matching content type. Leave this field blank to skip this filter test.s Use this option to remove each message attachment that does not have a matching content type. Requirements and formats are exactly like filter_mime_types.
Note: if you add entries to this list but don't add multipart to this list, any messages with attachments will be rejected by the pass filter.s convert_html_to_plaintexts Should Mailman convert text/html parts to plain text? This conversion happens after MIME attachments have been stripped.s filter_actionsO Action to take when a message matches the content filtering rules.sJ One of these actions is take when the message matches one of the content filtering rules, meaning, the top-level content type matches one of the filter_mime_types, or the top-level content type does not match one of the pass_mime_types, or if after filtering the subparts of the message, the message ends up empty.
Note this action is not taken if after filtering the message still contains content. In that case the message is always forwarded on to the list membership.
When messages are discarded, a log entry is written containing the Message-ID of the discarded message. When messages are rejected or forwarded to the list owner, a reason for the rejection is included in the bounce message to the original author. When messages are preserved, they are saved in a special queue directory on disk for the site administrator to view (and possibly rescue) but otherwise discarded. This last option is only available if enabled by the site administrator.( s categorys Nones mm_cfgs TEXTFIELDWIDTHs WIDTHs _s actionss% OWNERS_CAN_PRESERVE_FILTERED_MESSAGESs appends Radios Texts tuple( s selfs mlists categorys subcats actionss WIDTH( ( s) /var/mailman/Mailman/Gui/ContentFilter.pys GetConfigInfo s ! c C s | d d f j olg } x+g i } | i D] } | | i q0 ~ D] } d } | i d } | d j o | o d } n | d j o` g i } | i d D] } | | i i q ~ \ } } | p | o d } q n | d j o d } n | o | i t d qM | i | i i qM W| d j o | | _ q| d j o | | _ qn t i | | | | | d S( Ns filter_mime_typess pass_mime_typesi s /i s# Bad MIME type ignored: %(spectype)s( s propertys typess appends _[1]s vals splitliness ss strips spectypes oks counts slashess splits lowers maintypes subtypes docs addErrors _s mlists filter_mime_typess pass_mime_typess GUIBases _setValues self( s selfs mlists propertys vals docs slashess _[1]s oks maintypes subtypes ss spectypes types( ( s) /var/mailman/Mailman/Gui/ContentFilter.pys _setValue s, 4 B c C sJ | d j o t i | i Sn | d j o t i | i Sn t Sd S( Ns filter_mime_typess pass_mime_types( s propertys NLs joins mlists filter_mime_typess pass_mime_typess None( s selfs mlists kinds propertys params( ( s) /var/mailman/Mailman/Gui/ContentFilter.pys getValue s ( s __name__s __module__s GetConfigCategorys Nones GetConfigInfos _setValues getValue( ( ( s) /var/mailman/Mailman/Gui/ContentFilter.pys ContentFilter s j N( s __doc__s Mailmans mm_cfgs Mailman.i18ns _s Mailman.Gui.GUIBases GUIBases NLs ContentFilter( s ContentFilters mm_cfgs NLs GUIBases _( ( s) /var/mailman/Mailman/Gui/ContentFilter.pys ? s