Content filtering
Policies concerning the content of list traffic. 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.
Description	Value
Should Mailman filter the content of list traffic according to the settings below? (Edit filter_content)	No Yes
Remove message attachments that have a matching content type. (Details for filter_mime_types)
Remove message attachments that don't have a matching content type. Leave this field blank to skip this filter test. (Details for pass_mime_types)	multipart/mixed multipart/alternative text/plain
Should Mailman convert text/html parts to plain text? This conversion happens after MIME attachments have been stripped. (Edit convert_html_to_plaintext)	No Yes
Action to take when a message matches the content filtering rules. (Details for filter_action)	Discard Reject Forward to List Owner Preserve