The Content filtering option controls what kind of content will be allowed to pass to the list. You can use this section to prevent any MIME types you don't wish to allow.

If this function is enabled, Mailman will first compare all messages' attachments against the filter_mime_types option. Any matches will be stripped from the message. Mailman will then compare what is left with the pass_mime_types option. Anything that does not match will also be stripped from the message. Any multipart attachments are checked next, and removed if they are empty. If this leaves the main message empty, it is then discarded completely.

Finally, if the convert_html_to_plaintext option is enabled, Mailman will convert the message to plain text before sending it to the list.


The filter_content option controls if Mailman will filter messages send to the mailing list.


The filter_mime_types option is compared to all incoming messages by Mailman. Matches are stripped from messages.


The pass_mime_types option does another check of the attachments. However this time anything that does not match is stripped from messages.


The convert_html_to_plaintxt option tells Mailman to strip all HTML from the message and deliver it as plain text.


The filter_action option tells Mailman what to do if filter matching above causes the message to not be sent to the list. Discard simply discards the message, Rejects discards it and sends a notice to the message sender, Forward to List Owner forwards it to the owner for review, and Preserve places the message into a queue directory for the Site Administrator to view but is otherwise discarded. While the Preserve option is enabled, maintenance of a Mailman list is the responsibilities of the owners.