[Mailman-Users] To use or not to use content filtering

Mark Sapiro mark at msapiro.net
Fri Jan 28 00:45:54 CET 2011

Andrew Hodgson wrote:
>However, over recent months we have had some issues with content filtering on some lists, with users who send emails with disclaimers, where the disclaimer is added as an attachment to the message, and Mailman appears to strip off the actual message, leaving the disclaimer to post to the list, and of course adding in the standard footer.

I suspect what is happening here is the poster sends an HTML only
message. His organization adds a disclaimer as a separate MIME
text/plain part and Mailman's content filtering is removing the HTML
leaving only the disclaimer.

You can avoid this by adding text/html to pass_mime_types and making
sure that collapse_alternatives is Yes so multipart/alternative with
text/plain and text/html subparts is still replaced by only the
text/plain and setting convert_html_to_plaintext according to your
desire to have unfiltered HTML converted.

>Are people using content filtering in lists where most people are using MS products, and a suitable antivirus package on the MTA as well as a low posting size limit, or are there any tweaks I can make to the content filtering settings that may get some of this stuff through?

Agressive content filtering can help with keeping viruses and other
malware off the list, but a good malware scanner is probably
preferable for that purpose. Content filtering is useful for keeping
unwanted things off the list. Unwanted because you don't want to use
bandwidth and archive space for images, HTML, proprietary document
formats, whatever.

Note that if "most people" are using MS products, and they are not
restricted, they will post .doc, .docx, .xls and .xlsx attachments.
Where does that leave the minority who don't use MS products, not to
mention those whose MS products are old enough that they can't handle
the XML formats.

All MUAs can sensibly display plain text. The same cannot be said for
other content types.

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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